lowbee

I would agree with you. I thought neither Kline nor JCR+CG filtered OAP drone in valve closed mode anyway so I don't see the value of switching to CG x-pipe in your case unless I misunderstood and your current setup do drone in valve closed mode.

UncleDude

Good work! I too have an email in to Cargraphic with a similar question. I have a reply, but Thomas asked some clarifying questions, but it seems you have the answer. Looks like any x-pipe system is going to have more resonance than the boxes (makes sense I suppose). What I’d like to know is what’s happening in that triangular or oval box, just mixing, or is there a perforated x-pipe in there? That’s what I like about the Soul muffler, it is an X valves open and an X inside the muffler. John at soul did tell me there was more resonance than stock, but there’s no real way to quantify it without trying it I suppose, and on top of that we all have different thresholds of annoyance.

When I listen really closely to the stock system, I do hear the hum / drone around 2000 rpm but it is not bothersome to me - to be frank I just consider that “exhaust” sound. But if you double the intensity of that sound would it be annoying? Probably? I hope to ride again in a week or so in a GT4 with the JCR rear section, to confirm my initial experience. Then I think I’ll know what my plan is - this thread has been very helpful!

@IL_Pete if you dig into the Soul rear section, please let me know what you find out.

lowbee

Just listening from YouTube video I found the CG x-pipe racing has a higher pitch than Soul valved exhaust, I am not sure if it is the recording or the environment these cars drive in. I wish I could compare the 2 exhausts side-by-side. If someone has listened to both systems in person, please chime in

IL_Pete

So to clarify in that regard, the JCR + CG OAP does drone a bit with Valves Closed. It drones more with Valves Always Open with the VC.

The Kline never droned ever, Valves Open or Closed. The Kline is the best I have heard in that regard! Unfortunately the Kline was a little too loud above 5100 RPM for me, and my bad left ear. I am pretty certain that without the sensitivity of that bad left ear, I would have declared the Kline to be perfect and would have been done experimenting!

I should also clarify that the bump in volume intensity at 5100 RPM is not unique to the Kline. That comes from the engine, it happens with all of the systems. It is just quieter there with the JCR + CG OPAs than with the Kline.

IL_Pete

I would agree the CG X-Pipe Racing has a little bit of a higher pitch than the Soul, as does the JCR and the Kline, which is the primary reason I had focused in on those 3.

The Soul does sound pretty good in the latest Flat6 demo. I like that they did it inside the car with windows closed and with windows open. I wish they would have done longer demos inside the car at various RPMs.

The Soul has been declared to have a little bit of Drone, probably similar to what I experience with the JCR. So I don't plan to try that one, because of that. It was on my list earlier in the year, I just opted to go JCR because I wanted that higher pitched high RPM tone. The guys at Soul are terrific to deal with, I spoke to John G there at length about the 718 Exhaust and challenges, and the work they were doing with experimenting with the Sound Symposer Delete, back when that all started.

Back to the CG options, I would probably go for the CG Non-X-Pipe Track/Competition if I tried one, the quieter of the 2 ones declared to have no drone with the triangular box. But I can't find any demos or reviews of that particular one, not without being combined with headers. The demo of the Touring (in the video posted above, the louder version) sounds decent but not as high pitched as the X-Pipe Racing.

As I mention above, I might also do is "start over" when the Spyder comes in next spring, to see what difference the non-lined soft top makes. I would start with no SS Delete and just do the VC and CG High Flow Filter OAPs, and then incrementally add the JCR, and then decide whether to do the SS Delete again, and THEN potentially try another back box if not satisfied with the results...

Or I may get bored and try the CG before the Spyder comes in.

SpydrGuy

Have you thought about adding street headers with the stock OAPS and JCR rear? The headers will add the extra volume and HP you're looking for and the stock OAPs seem to provide pretty good attenuation of the drone.

mprog

This is a config I’ve been pondering lately. Jonny told me the OAP’s burn off the smell of catless headers. So may be no downside.

IL_Pete

I have thought of that, but I am concerned that with Valves Open that would be too loud for my bad ear, even with Stock OAPs.

I am keeping that in the back of my mind, though. I will probably have a revised notion of what the perfect volume and sound is for the Spyder with the top down, as that comes in next year.

IL_Pete

Update here - @tdlondon installed my Kline system on his GT4. He has the SS Delete and a VC, and had the Fabspeed Exhaust and OAPs. The Fabspeed setup sounded great at high RPMs, but had a decent amount of drone around 2K RPM.

He took me for a ride Sunday - the Kline system sounded AMAZING with his GT4! Better IMO than with my GTS, with the VC open all the time it sounded great cruising around, and it sounded pretty epic under hard acceleration and at higher RPMs. It had significantly more motorsport theater with the less sound deadening of a GT4 versus my GTS. He liked it enough that he declared it wasn't coming off and bought it from me. Curiously I did not really hear than resonance at 5100+ RPM that bothered my bad ear. But we only went for a 15-20 minute ride, maybe at 1 hour+ my ear would be bothered.

It seemed very different with his car. But also I wasn't the one driving either, I think that makes a difference in the experience. Hearing his car with the Kline reinforces to me that all of us here talk about comparing exhaust systems, but I think they yield different results on the 4 different versions of the 4.0.

As with my car, there was zero drone at 2K RPM. There was some increase in the bass of tones under throttle at 3K RPM give or take, also like my car, but nothing I would call drone. That Kline system sure is great with regards to reducing/eliminating drone!

(I was jealous it sounded better on his car than mine. But that's okay, it proves I really need a GT version of the 4.0. I will be okay, I have a Spyder on order now!)

Update on more time with my setup of JCR (Silenced) plus CG High Flow filter OAPs - I am really liking it! For sure it has some drone around 2K with the windows closed, even with the Valves closed. It is amazing to me how much of a difference windows open or closed makes. I guess I will just always have the windows down, or also the drivers window fully down and the passenger window down a few inches yields about the same results. (Unless of course it is raining or snowing.)

Other observations: It seems to shift more smoothly with this combination. That seems weird to me, but it feels great! Also that increase in volume I experience with the Kline at 5100 RPM is not just with the Kline, it exists with this setup too, it must just be the engine. The difference is that the Kline reacted to it differently, it had a resonance there that bothered my bad left ear, this combination does not.

This combination is my favorite with regards to volume and tone at high rpm on the spirited country road drives. The tone is really terrific! Also I had normally been driving it Sport Mode because I liked the extra burbles. I switched the last few drives to Sport Plus, because I have ordered the Spyder, and the Sport Plus mode is much more like the standard mode of the GT4 and Spyder, so I wanted to check that out. That has been an interesting change. The burbles are reduced by a decent amount, but they are still there. The Sport Mode has a stronger *initial* throttle response. But you get used to the reduced initial throttle response quickly in Sport Plus, and once you do, while the initial throttle response is reduced, the overall feeling is more purposeful and ballistic, it's like you have to go after it harder to accelerate more briskly, and once you do, it is more aggressive than Sport Plus. It is very rewarding! That translates through to the throttle tone, it also sounds more purposeful and ballistic when you get after it in Sport Plus. I will be keeping it Sport Plus. (I have the Design-9 Memory Module, which remembers my previous settings, very helpful!)

I think I will be fine in rolling with this setup for a while, and then carrying this forward to the Spyder and reevaluating from there...

flynlo

Thank you again!!! Just makes me feel really good about my Kline choice for my Spyder. I did get stainless....I don't see how it could be terrible different. I cannot wiat to hear that thing shriek with the top down!!!

tdlondon

Thanks so much Pete! This opportunity of trying out the system before making a decision was fundamental! I agree with you that the Kline poses the best balance of very little to no drone at the "cruising RPM" 2k-3k range, while still sounding amazing at WOT. I think the free-flow resonators mounted on the Kline OAP are the responsible for killing the drone we hear comparing with the straight pipe Fabspeed/Soul OAP, while not restricting the flow and creating as much back pressure, thus maintaining the feeling of additional power and torque. Then on the exhaust, you see that the valves open path of the Fabspeed dumps directly out, there is no crossing of the pipes, which creates more of that 2x 3 cylinder pitch, while the non-valved path crosses in the middle and then go through a smaller resonator before it goes out to the tips. On the Kline, both straight and valved paths get merged. The non-valved path goes through a larger resonator and then gets mixed with the other bank before exiting through the tips, while the valved path doesn't go through the resonator but meet the non-valved path before it crosses the other bank.




After driving around 100 miles with the new setup, I still believe Kline is the best choice. Talking exclusively about race track use, I think the Fabspeed provided a more engaging experience when driving constantly at 4500-8000 RPM, pretty close to the GT3-like sound. I think by not mixing the valved path (meaning at valves open you have the separate 3 cylinder pitch) it created more vibration on the sound, more spaced pitch, which felt electrifying on the race track! I haven't been on the track with the Kline yet, so unfair compare with very limited data points, but by pushing to redline a few times and downshifting, there is just something more raw about the Fabspeed at this range. It also had more burbles and braps. Still, in the grand scheme of things, my use is less than 50% track (especially in the Midwest now since I moved, compared to my first year in CA with this car and track events year-round!), and the relief of having no drone at that city range is totally worth it. Can now take the wife for a nice dinner on this car without her wanting to not ride the car ever again. And the high RPM range is also spectacular! Just maybe 1-2db quieter overall.

In the coming weeks I'll experiment putting the sound symposer back on and try it with the Kline and see what it does. Then based on that experience, I'll put pencils down on my exhaust quest (until who knows I come across some headers to experiment with)!

UncleDude

Nice work guys, I find this modular exhaust system endlessly fascinating.

IL_Pete

Good write-up! Agree that the Fabspeed setup was pretty epic at high RPMs, in an angry sort of way!

lowbee

I haven't heard Fabspeed valved exhaust in person but looking at their design, it is pretty much just straight out for the open path so I would expect any exhaust with similar setup on the open path would sound as epic at high rpm. Thoughts?

tdlondon

I would think so. SOUL for example crosses both banks on both valved and straight paths. I think Fabspeed gives this "angry" sound from having a pretty much straight out of the OAP path to outside.

My Fabspeed setup is for sale btw Pair of OAP and the valved exhaust above.