IL_Pete

So I have had my 2021 GTS for just under six months, and have 8,000 miles and change on it. I don’t normally put this many miles on a car, as I don’t have a commute, I work from home. But I love this amazing car so much that I can’t stop driving it. I go for 5-7 one-hour-plus drives per week on Country Roads in IL, just for the fun of it. As much as I love this car, probably the thing I disliked the most is the stock exhaust, and with that the stress of figuring out how to best “fix” it, with all the options available (almost too many!). I have been thankful that I have you guys here to educate me, otherwise I am not sure I would have bought and kept the Cayman GTS 4.0, without knowing the subpar Exhaust note could fairly easily be addressed.

I did the Soul OPF Delete OAPs and the Soul Valve Controller at the same time at about 1,000 miles. I just switched that to the JCR Silenced Valved Exhaust with the stock OAPs, with the Soul Valve Controller still installed. Along with that, I also had my installer do the Sound Symposer delete. So I have 7,000 miles on the Soul setup, and in the last week I have many hours and several hundred miles on the JCR setup. Both are great! I will attempt here to compare and contrast the two, and will work to post a couple of comparative sounds clips, when I get a chance.

The Soul OAPs combined with the Soul Valve Controller (which I will refer to as “VC” for the rest of this post) are a great upgrade, and particularly a terrific value relative to an exhaust, particularly the JCR exhaust, which is pretty expensive due to the Titanium Construction and the Exchange Rate. I did them both at once. I wish I had done the VC first, and then the OAPs, to compare and contrast both. That was the original plan actually, given the advertised 6-8 lead time when I ordered the OAPs. But I got lucky and the OAPs shipped right away with the VC, they had a set left from a batch they did.

I can’t stand the PSE control logic and tone, it is so binary open or shut and the sound is SO different, it sounds so weird transitioning from closed to open and back. Really bad, shame on Porsche for releasing the 4.0s like this. (Perhaps intentional as they always make sure to hold back the 718s to not be as “good” as the 911s. But with this exhaust fix, the CGTS 4.0 is better for me than ANY 911, short of a GT3!)

The Soul OAP+VC setup fixes that, I left the Valves always open about 90% of the time. I only closed them if I was trying to be stealthy in the neighborhood (usually only in the early mornings), or if I was worried about attracting unnecessary attention from law enforcement. But the sound difference with the PSE controlling the valves with PSE turned on, and wimpy sound of PSE turned off are both pretty pathetic IMO, so thus running with the Soul VC forcing the Valves always open being the defacto mode of operation.

The Soul OAP sound is very good all around. Sporty and good sounding at modest RPMs, and absolutely GLORIOUS at higher RPMs! The great sounds above 3500 rpms are more so RPM dependent, not throttle level dependent, which will become relevant later here. The amount of gloriousness is a linear curve up and to the right from 3,500 rpm all the way to 7,800 RPM.

Also of note, the Soul OAPs match really well with Sport Mode on the GTS 4.0, which has a significantly higher amount of burbles, pops and cracks than Normal or Sport Modes. Hard accelerations from first to second to third would get loud cracks from first to second (about 50% of the time) and sometimes from second to third. The Burbles are constant on overruns and sound great. I drive in Sport Mode 95%+ of the time. Almost 100%, really. Sport Mode has a much sharper throttle response than Sport Plus, which I love. And that is where the max burbles, pops and cracks happen, by Porsche design - Sport is for maximum fun, Sport Plus for maximum performance and best lap times.

I have really loved the Soul OAP + VC combination! But I worried it was a bit loud, on my country drives at higher RPMs, it seems very loud, and attracts a lot of attention, I am sure it can be heard for miles. So I wanted to try something not quite so loud.

So now for the JCR Silenced Valved Exhaust, with the factory OAPs and the Soul VC, with the SS Delete. It is also very good, and fairly different. First of all, let me start with the big surprise. I was focused on the sound. I had read the JCR thread several times, and was aware of the claim of HP and Torque gains. I didn’t think anything of it, really. But upon installation and first drive, I was blown away by the additional torque and hp, and as a bonus an even livelier throttle response in Sport Mode. The feel of it is more so the torque everywhere, with the livelier throttle response, but particularly the torque in the lower RPMs. I drive on spirited country road drives almost every day, and the tires break loose much more easily from a stop, or accelerating out of a corner. (Jonny - I will send you a bill for a pair of rear tires. ) Also it just pulls harder, in every gear at every RPM. I was not expecting such a difference from that aspect. It was somewhat transformative for the entire driving experience, it just feels like a faster and livelier car now. No matter what I think of the sound versus other options, I am sure I now feel the need to keep it installed, for that reason alone.

The dynamics of the sound are very different. First of all, the VC helps a lot IMO, have those three modes helps (1 - PSE Control, Valves Closed; 2 - PSE Controlling Valves opening/closing, 3 - Soul VC forcing the Valves to always be open). Whereas the stock PSE has a huge difference in sound between valves open and valves closed, the JCR Exhaust does not, so the transitions are pretty seamless. It pretty much sounds great all the time in any of the 3 modes. Good, better, best. With the VC keeping the valves open all the time, even just tooling around at modest RPMs at modest throttle levels sounds terrific. Having the Valves open at lower RPMs where the PSE Control would have them shut adds a lot of low end to the sound, so it makes it sound a lot more sporty and fun, even with chill driving. If you want to attract a little less attention, turn that off, and it is quieter, but always a decent amount louder than stock with valves closed. So you do lose the ability to go in super stealthy mode, which I retained with the Soul OAP+VC setup, but I can live with that as I didn’t use it much, and when I did I was always annoyed with how anemic it sounded.

One point on the SS Delete. My impression of the sounds for the JCR Exhaust is that with just PSE control, it wouldn’t drone. But with the VC forcing the valves open all the time, there is a lot more low end to the sound - with the SS Delete, it doesn’t translate to drone inside the cabin. But I think it might a bit without the SS Delete. Also with the SS Delete, I do feel you lose a little of the engine and exhaust noise into the cabin, I have a tinge of disappointment and regret in losing that, it feels just a bit less connected in that regard. Keep in mind that the sound inside the GTS 4.0 is a lot different and at lower volume levels than the GT4, so I suspect the SS Delete has a different affect between the two models. It is fine, I just thought I would mention. The benefit probably outweighs the drawbacks.

The other big difference is while the Soul OAPs scaled in sound and gloriousness pretty much solely via RPMs, regardless of how hard you have the throttle down, the JCR Exhaust is MUCH more dependent on throttle levels. That “screaming like a demon” sound you hear in the demo videos / sound clips really only occurs at WOT. If you are in higher RPMs but accelerating more so gradually at 1/2 to 3/4 throttle, it sounds good to great, but is markedly different than the WOT throttle and tone. I am not complaining, overall across different driving scenarios I prefer the JCR Exhaust over the Soul OAP sounds.

I would describe it this way - Just tooling around town, the JCR sounds more exotic and sporty, without being too loud. A huge win for that type of driving. At WOT, it has that signature tone, and wins there too. But there is a spot in the middle where I prefer the OAPs - let’s call it 3,000 to 5,500 RPM in third or fourth gear, with modest throttle maintaining a speed. The OAPs are louder and have a more glorious tone in that scenario. Particularly with both windows down, with AWE Wind Diffusers. That nuance is very noticeable for me, as in the summer months I drive with both windows down most of the time. In third gear, the exhaust is very present with the JCR and sounds great, with windows down. In fourth gear, which results in a lower RPM and lower throttle level, sometimes you can’t as much hear the exhaust at speeds of 50 to 70ish mph, and that for me is very noticeable after 5 months and 7K miles with the previous setup driving like that. (Also note that the AWE Wind Diffusers are a MUST HAVE for that - I couldn’t hear the Exhaust with the Soul OAPs until I installed those, HUGE difference!)

With windows up, I don’t really have that issue, so if you are not doing what I do, probably a non-issue. Also I tried the drivers window down and the passenger window up, and that made the fourth gear sound and feel more present. There is no buffeting with that setup (with the wind diffusers) up to 70 mph, but at 70-80 mph+ (on my private airstrip) there is some buffeting. (I did get the Silenced version, perhaps if I would have got the non-Silenced one, it would be a little louder and I wouldn’t as much have of that “fourth gear / windows down” nitpick.)

In third gear at speeds of 50 to 70ish, the livelier throttle response is really terrific, and makes the car feel and sound great - it is much more fun going 55 in a 55 zone, much better with regards to ticket avoidance!!

Looks - OMG the JCR looks amazing! I got the Black Inconel tips, and they look perfect with the Black Diffuser. Better than the stock ones. And of course the exhaust itself turned blue under the car looks amazing. (Pics to follow!)

Lastly on JCR there are burbles in Sport mode, but much less than with the Soul OAPs, and the cracks and pops are completely gone. So the JCR Exhaust with the stock OAPs is more Motorsport and sophisticated, and the Soul OAPs are a little bit more “Hooligan”. I would have thought that that would be what I prefer, but I am finding I really miss the greater amounts of burbles and pops and cracks of the Soul OAPs.

I am pretty sure that the JCR Silenced Valved Exhaust will be the right volume level for me. But I can’t help but wonder, what would the combination of the JCR Exhaust *AND* the Soul OAPs sound like? Probably epic, but also probably too loud for me. Still, I am going to try it.

Conclusions/Recommendations:

1. A Valve Controller by itself is a MUST HAVE as soon as possible after delivery. Very inexpensive, and no one should have to be forced to deal with the pathetic stock tone and the maddening PSE control logic.
2. OAPs are the best “value” mod to add from there. 1/2 to 1/3 the cost of a good exhaust, and really amps it up for great improvements to volume and tone. And the Soul team is fantastic to work with, great guys.
3. The JCR Exhaust is a fantastic option, but really in the “if money is no object” category, the cost in the US is high, eye-wateringly so. You get what you pay for, for me, it is worth it.

I will follow with some pics and sound clips. (And later, a JCR Exhaust + Soul OAP update.)

Whew, that was a lot to type! Hope that is helpful.

IL_Pete

Pics:

lowbee

Thanks for the detail review Pete. Can you comment more on drone with the valve closed between 2k-3k rpm with both setup (or perhaps including OEM if you remember) ?

IL_Pete

No recollection of any significant drone with full OEM, Closed or Open.

No significant drone with the Soul OAP + VC, with PSE Control and Valves Closed or Open, or always Open via the Soul VC.

No significant drone with the JCR + Stock OAP + VC + SS Delete, with PSE Control and Valves Closed or Open, or always Open via the Soul VC - with the comment above that with Valves always Open via the VC it has more low end, and seems like their might have been drone if I didn't have the SS Delete.

Where I think people get into drone issues is more so in combining OPF Delete OAPs with an aftermarket Exhaust (with or without a Valve Controller). I experienced that in a friend's car, it had significant drone in that 2-3K RPM range. There, the SS Delete likely helps, but may not eliminate it, as others have reported.

As I said above, I will try the JCR + Soul OAP + VC + SS Delete combination, likely next week, and report back.

Mike0105.

Great review, can't wait to hear your thoughts when you eventually try the JCR paired with the SOUL OAP's
Mike

IL_Pete

Okay, I stand corrected. With windows closed, valves in any position, there is some drone with the JCR setup when at about 1800 to 3000 rpms, particularly when under throttle and the engine is bogged down trying to accelerate. I just went out for 1.5 hour drive, and played around with different scenarios at different RPMs. It is not bad drone, not like I have heard for instance on the other car with the Exhaust + OAP + Valve Controller with no SS Delete. But it is there, particularly in 4th, 5th, 6th gears. (Dust flew out when I tried 6th gear - it has been about 5 months since I was in 6th gear. )

I realized today that I don't typically drive at less than 3K RPM in 3rd gear or higher. I am typically in 3K to 6K RPM in 3th and 4th, never in 6th, and rarely in 5th (highway only). Around town running errands, 1st, 2nd, 3rd. Country Roads, rip through 1st and 2nd, cruise mostly in 3rd, sometimes 4th (mostly just to have an excuse to shift to 4th and then soon back to 3rd, or if at a speed where 3rd starts to sound silly). Windows always fully down when it is not raining, since about April. But even with windows up in the RPM ranges I typically drive in, there is not really much noticeable drone. I am not at all trying to be in those RPM ranges to avoid drone, that's just the way I like the drive it. I like how the car feels in an RPM range where the throttle is needed to be above the point of balance, where if you backed off you would immediately get engine braking (and burbles!). The car feels very lively there (and sounds great), so that's where I keep it. (The gas mileage result in driving like that by the way is about 18 MPG, give or take .5 MPG, for every single drive.)

So maybe I am not the best person to ask about drone.

IL_Pete

Funny, after I made the post above about drone, that same evening I watched this video:


Sort of the same process I went through, made a review on the Exhaust options, and then later when asked about drone I drove again and researched - and found that in some driving conditions there is some drone, but just not in scenarios I typically drive in.

Different exhaust setup, also sounds great, similar context and story...

UncleDude

Seems like a fair and balanced report. The GT4 I drove, and drove in, has the same set up as you and it did exactly what you described. That owner doesn’t care in the slightest and feels the glorious tone more than makes of up for that minor nuisance.

IL_Pete

Sound clips as requested! Both are about the same route, I believe. (I think you can here tires squealing at the same spot from a stop on a left hand turn, LOL... )

I apologize for the mediocre sound quality. Both were recorded from an iPhone (with the built-in microphone) on a Rennline Phone Mount to the left of the PCM. Both windows were down, which creates a lot of wind noise but also makes the exhaust sound front and center on the inside of the car. For the JCR clip, it occurred to me to put the Passenger Window up about 30 seconds in, which reduces the wind noise thereafter.

EDIT: Also if you listen closely, on the JCR clip you can hear me hit and bounce off of the Rev Limiter at the top of second on the first run (on the private airstrip). Whoops!

In extracting these two clips this morning and listening them back to back a few times, my reaction is that both setups sound pretty great!

If they sound so great each on their own, holy cow, what will they sound like together? That is next on the GTS 4.0 exhaust journey...

flynlo

You're a rockstar Pete!!! Thank you so much for doing this. I was torn. I do not even have the car and am already stressing about the exhaust and the disappointing noise of the OEM setup. I have to admit, both clips sound pretty damn badass. I think you have helped me make up my mind. The JCRs sound incredible. But so do the OAP. Obviously, the OAP with VC is quite an attractive set up with respect to value and that is the way I will likely go. I look forward to your OAP+JCR exhaust review. Gonna be crazy I bet. My only fear would be how loud it is. Thanks again!

PS....what is even crazier is that the audio quality isn't that great....so I imagine it sounds amazing in the real thing.

Westcoast

Initially I ran just the JCR rear section (Silenced Race Pipes) with the valve controller and found drone to be minimal but definitely there, being able to close the valves in the Drone Zone really helped. After a couple of months I added Akra link-pipes (GPF delete), and the drone 'potential' increased immensely, now the VC was mandatory to help keep it in check, the sound of the system is incredible, much more intense but I am thankful that with the silenced rear section and valve controller I can close the valves and enjoy a reasonable sound experience when desired, otherwise for me the Akra OAP-GPF delete would not have stayed on the car.

Looking forward to your impressions...

IL_Pete

Thanks, Westcoast!

You give me hope that I might dig it with the JCR Exhaust + the Soul OAPs.

Do you notice a big difference (with the VC turned off letting the PSE control do its work) between PSE valves open and valves closed? I can't tell much difference, if any at all, between the two settings, in my current setup with the JCR Silenced Valved Exhaust with the OEM OAPs. I am going to have my installer look at it when I take it back in, to make sure it is working properly. (I can hear something mechanical switching when I change the setting while idling, which to me indicates something is happening...)

EDIT: Just got back a great 2 hour drive today. (Epic, really - this exhaust setup ROCKS!) I figured out the issue I was having yesterday. I use the HomeLink buttons to turn the VC on and off. It has always been hit or miss, some days it works fine, some days not so much. Today I tried the Soul-supplied Keyfob, which always works great. Once the valves were properly shut off, I could hear the difference with the valves closed, much quieter, especially so versus the valves always open with the VC. I used it pulling out of the neighborhood, and always while going into a small town downtown with low speed limits to get gas.

Westcoast

I just read your EDIT, I second you observations and I thought that you would warm up to the sound... you can now hear how well the silenced section works when the valves are actually closed... I think that this really helps to keep the sound reasonable when you need it, loud doesn't always attract the attention you want.

And about the Homelink buttons, thanks for this confirmation mine is the same, I too have the key-fob programmed to them and also find that it can be hit an miss when using them but the fob itself always works (I keep it in the car). I think the reason for this is that the antenna for the VC is behind you and the Homelink transmitter broadcasts forward of the vehicle (this effect is also noticeable on our Macan and its door control), I know that it is not range per say as I can open the garage from nearly a block away when facing the garage door, but sometimes it won't close if the back of the vehicle is facing the door.

IL_Pete

Thanks for the explanation on the Homelink buttons. Makes sense that they are directional. Yesterday I went for a long drive and use the Keyfob, it worked perfectly. I guess I will use that going forward...

IL_Pete

Update: Got the Soul OAPs installed and went for 3 drives, one home from the shop, suburb driving and expressway, 1.5 hour country road spirited drive, and then another 30 minute country road spirited drive with my son.

It sounds amazing for the spirited country road drives! Ferocious, bombastic, epic are words that come to mind. The burbles are more dramatic. The pops and cracks are back. The volume is a decent amount louder, especially with the valves left open all the time, and significantly so at high rpms. The cold start is pretty epic with the valves open, and not horribly loud with the valves closed. At 3500 plus RPMs it sounds terrific. At 4500 plus it sounds incredible. At 5500 plus it is mind blowing!

Also a note re performance. I could feel that it was faster still than with just the JCR exhaust. What's weird is, I don't think I felt much torque/HP increase from just the OAPs, maybe a little. But per my posts above and on the JCR thread, I was shocked at how much I felt from the JCR Exhaust and the stock OAPs. I wasn't thinking about HP and Torque from the change today, I was focused on the sound, loudness and listening for drone. On the spirited country drive, I could feel it big time, particularly I the upper RPMs. I bounced off the rev limiter hard a couple of times, because I just wasn't used to how fast it gets there.

That all said, I don't think I will keep them OAPs installed. There is a decent amount of drone at 1800 to 2200 RPM and again some (to a lesser extent) from 3200 to 3800 rpm. It is worst when the engine is bogged down in higher gears. I mentioned above that was to some degree with just the JCR exhaust, but it is significantly more dramatic with the OPF Delete OAPs, in all Exhaust modes. Enough so that that makes me want to go back to just the JCR Exhaust. If it were my weekend toy for just country road drives, I would probably keep it with the Soul OAPs, but I also use this car for running errands, a decent amount, it is my only car, for now. (M3 Manual on order for Winter/Family Car, but even when I get that, I want to be able to drive this around town comfortably.)

But that's not the only reason. The other reason is while the JCR Exhaust + Soul OAPs is pretty darn awesome, it is just "too much" for me. A little too loud, a little too much of an attention grabber, which extends to potentially grabbing the unwanted attention of law enforcement. It sounds so great and loud that when going 55 in a 55, it sounds like you are going 80, seriously. When going 65-75 in a 55 in third gear, it probably looks and sounds like you are going 100+. Also, it sounds sooooooo dang good above 5500 RPM, that I found myself downshifting from 3rd to 2nd on the 55 MPHs just to get that sound, then of course you accelerate and shift again to third, look down and you are doing over the speed limit by an uncomfortable margin, and also that whole process is incredibly loud. It eggs you on and pulls the Hooligan out of you - I couldn't control myself! The JCR Exhaust itself sounds pretty fantastic, and doesn't have that effect on me, at least not nearly as much.

For some of you, what I describe above might be just perfect (other than the drone). My son LOVED it! But he knew I would change it back, for my tastes. If I had Diplomatic Immunity of some sort, I would keep it with this setup. Short of that, I should probably go back to the Stock OAPs.

Lastly and probably least significantly, having the OPF Delete OAPs takes some of the specific JCR character out of the exhaust, the OAPs overpower the tone that is pretty unique to the JCR exhaust, at least until over 5000 RPM or so. While I prefer the volume and rowdiness of the combination, at 3500 RPM to 5000 RPM, the tone has a lot of Bass in it, where with just the JCR, it has that very unique and specific tone, which I have really come to love.

I will enjoy this madness for a few days, and then reel it back into the JCR Exhaust with the Stock OPFs, which is pretty darn fantastic in and of itself. I had fun trying this though, I needed to do that!