Soul Performance

Directory of Top Posts:

• Competition Over Axle Pipes / Competition Headers Development
• PSE Muffler Explanation
• Race Exhaust Development
• Valved Rear Exhaust 1 | 2
• Valve Controller Solution 1 | 2
• Obsessed Garage OAP Impressions
• Resonated vs Non-Resonated Race Exhaust
• Back Purging Welds Explained
• Long Tube Street Headers Development
• Sound Symposer Delete Testing

Hello Everyone,

Say hello to our new R&D project, the 718 GT4! There’s been a lot of talk over the last few months about this car and a lot of discontent with some popular YouTube videos comparing the 718 GT4 and 981 GT4. Let’s dive right into it. More photos and videos will be forthcoming as we progress with development. The new 718 GT4 (and Spyder) as shown here now has three modular exhaust sections compared to the previous 981 generation that had two. Starting at the front, we have the headers and primary cat assemblies. The exhaust then bolts to a set of over axle pipes with canisters at the end, which then connects to the factory valved muffler system.
..Some of the immediate low hanging fruit that pops out is a rather restrictive merge collector that essentially has all three primary tubes hitting a wall, at which point the exhaust flows into a cat core just as dense as they have been before on previous Boxster / Cayman generations. We’ll get a bit more in depth into this once we take a closer look at the headers this week and come up with some prototypes. We will be making a catless long tube competition header and street header utilizing HJS HD 200 cell cat cores. With the superb new rear aero improvements, clearance is TIGHT from the headers to the underbody panel, so we may have to get creative with this header/merge collector design..These factory over axle pipes appear to have an OPF matrix completely unmonitored by the computer system, unlike the Euro spec cars with monitored OPF cores. These were the first to go, and as you can see and hear this is going to be one of the best returns on investment for sound and performance improvement with a single product replacement. Uncorking these over axle pipes makes much better use of the factory valved PSE muffler. It maintains a very reasonable, almost factory-like sound inside of the car with valves closed, and valves open it is quite transformed. Eliminating the restriction of the headers and over axle pipes and keeping the factory PSE on the 718 GT4 / Spyder will without a doubt be the golden ticket setup for this platform..Yes, California and European owners we’re listening! For you Cali folks, until we confirm these over axle pipes don’t have a true emissions control device in them we realize this is the only piece of the exhaust you can “technically” replace while passing inspection / emissions as there are CARB visual certifications requiring factory only components, even though you have a 6 year grace period if I recall before you have to go in for that. For our European friends in particular, we know you can’t touch the over axle pipes due to the monitored particulate filters as there is no high flow aftermarket replacement for those units yet (people are working on it) so that leaves the headers and the rear system. This factory PSE muffler is pretty well designed, albeit pretty funky looking to clear the rear diffuser. With valves closed it significantly cuts down on sound through the muffler body and with valves open it essentially bypasses the entire muffler assembly (diagrams / photos / video on this soon). However, if you’re looking to stay emissions compliant in your area it’s the only piece that can go and so it shall. We intend on offering several different versions of muffler replacement on this car - something wild for those that just don’t care and want to drop as much weight as they can, and something valved to have a similar wild factor but the ability to tone it down and take the edge off the sound to fly under the radar. The space constraints with the diffuser will make this complicated, but we’re up for the challenge and will start playing with the rear exhaust configurations once we complete header and over axle pipe development..Unlike all the previous Boxster/Cayman generation that had welded on tip assemblies, the 718 GT4/Spyder has bolt on tips...finally! This is going to be an easy project, and expect a flurry of different tip options from us soon to kick up the cosmetic appeal on the backside of the car.
.This is where things get interesting. European sound restrictions have been getting more and more severe over the last decade or so. Every time a new GT car comes out from Porsche, the PSE programming becomes more and more invasive in controlling the sound level of the car on full throttle. As many of you I’m sure have experienced on your previous Porsches, even with the PSE button pushed the programming will override this and close the valves until you reach a higher rpm range. The 718 GT4 is no different, and in fact it’s worse. With the button pushed, the 991 GT3 I drove the other week would shut the valves on hard throttle and then reopen around 3500rpm. With the button pushed, this GT4 keeps the valves closed until about 5000rpm. Now more than ever, the most inexpensive mod on sound you can perform on a GT car is unhooking the vacuum lines from the valves and plugging the lines so you don’t have a vacuum leak. Especially when unrestricting the exhaust upstream it makes a huge difference. Take the over axle pipes for example, below is a video where I drove this GT4 with our prototype over axle cat delete pipes. There are two takeoff clips in that video, the first take off clip is with the vacuum lines pulled and the valves in the default open position. The second take off clip has a large truck in it, during this one the PSE button was pushed/active for that takeoff and you can hear the valves close and then open at about 5k rpm. Completely different sound experience.

Now, for those who still want valve control but don’t want the PSE programming to override your fun we have one option now and are working on a couple others. We have our universal valve controller kit that simply works off constant 12V power, vacuum, and ground and has been used with great success on all of our valved exhaust systems for Porsches over the years. On this car it would serve to override the PSE button so it will no longer function, and the key fobs with our kit control the valves 100% closed or open. You can also sync the signal of these key fobs to your garage door buttons of the HomeLink system, so you can use existing buttons in the car instead of the key fobs if you so choose.

A second option may be an ECU tune. I’ve spoken with Scott at Softronic, our dedicated Porsche tuner. Many of you know him as one of the most experienced in the industry specializing in Porsche tuning for over 30 years. PCA Club Racing uses Scott to check all the ECUs to make sure no one is cheating, he also tuned all the Cayman Interseries cars, winning GTB1 cars, etc etc. He intends to look into the PSE programming itself to see if he can reprogram the ECU to simply keep the valves open 100% of the time when you press the PSE button. Along with all of the other benefits of software tuning Scott offers - such as power - this would be adding icing to the cake. We’ll look into this option for GT3’s as well

A third option is our friends over at DSC, those suspension tuning wizards you’ve all come to know and love for the DSC suspension modules to maximize the potential of Porsche’s PASM system. They have been working on an addition to the DSC module that allows you to have full control over programming your valves to do whatever you want when you want. We are keeping in touch with them closely moving forwards (as we are a DSC dealer!) and very much look forward to seeing how this turns out to play with improving the valve control and suspension on this new platform.

Our marketing guru Mike Spock and I will continue posting updates and teasers as we move forward with the project. Please comment with your thoughts and any questions as we go! Feel free to email me at johng@soulpp.com or text/call me anytime at 484 883 6197 to discuss this in more depth as we go.

Best regards,
John Gaydos

GAZZ

Re PSE hardware control option.
I would suggest not to allow the exhaust flap control option to stay in the close mode. This will cause additional heating of the exhaust if its closed and at high RPM.
Better would be to have 100% OPEN or OEM mode.
So instead of just wiring the soleniod coil to volts/ground connect it to the original control wire or ground, that will give the mode Open or OEM.
Use a plug / sockect breakout from the original solenoid + Earth.

Jim Rockford

Wow. Very thorough very transparent set of information and a well laid out post. A lot to chew on. Some info was assumed from gathering bits and pieces but some info new news. Great post, will be watching closely to hear what Soul can offer. I took a hard look at your product for my current car but shelved that due to my move to this 718 Spyder as an end game car. Excited to see what you can bring to the table.

Mojonito

When are you thinking these will be out? Looking for something for my spyder.

Flacht6MT

Great explanation and transparency, it's great to hear you guys are fully committed to finding solutions to what are the biggest issues with the sound. You guys are the first to finally say OPF delete pipes make a significant improvement, which we all were hoping. Can't wait to hear your other combinations with exhaust and headers soon, and smart idea on tip variations - that will be popular - @Soul Performance can you guys plan to provide an option for turn down tips that help with passing sound @ Laguna Seca?

Rennolazine

Subb'ed. This info is golden!! Thank you and we greatly appreciate the photos.
"A third option is our friends over at DSC, those suspension tuning wizards you’ve all come to know and love for the DSC suspension modules to maximize the potential of Porsche’s PASM system. They have been working on an addition to the DSC module that allows you to have full control over programming your valves to do whatever you want when you want. We are keeping in touch with them closely moving forwards (as we are a DSC dealer!) and very much look forward to seeing how this turns out to play with improving the valve control and suspension on this new platform."
^ This would in fact bet the shiZZnit.

Soul Performance

Gazz I was 100% on the same page as you, I preached that valves closed 100% of the time at sustained high rpm abuse would cause heat and longevity problems. That said, over the last year Bob Rouleau and the rest of his GT car track rat buddies up in Canada have been struggling to pass sound at Tremblant. The only way any of the GT cars could pass sound was to run the valves closed 100% of the time. And they did, every car every event all season. No difference in power in drag racing down the straight, no heat or longevity problems. Surprised me for sure, and I’m more comfortable with the 100% valves closed than I was before though still don’t recommend it. I’ll see if I can have Bob chime in here, I know he has a thread somewhere on it.

Thanks for the kind words Jim. We’re still in the early stages here and we’re not in a rush. We will keep everyone up to date with what we find moving forwards. I appreciate your consideration of us on your past and present car

Thanks for asking! We’ve only had the car for three days so far, so still in the early stages of prototyping and development right now. Though we would like to get this project done and brought to market sooner than later, we are not going to rush and ensure this is done in a quality manner. We will keep you and everyone else up to date as we put together the final production units and determine pricing

Best regards,
John Gaydos

Illusive991

One question after reading the detailed explanation above: If you unhook the vacuum lines, does that essentially negate the use of the PSE button (i.e. it is now always 'on' regardless if the button is pushed) or does that prevent the valve from shutting when accelerating up to 5,000 RPMs when it opens up again? If you do unhook the vacuum lines, do you remove them completely and plug both ends or just one side? And what do you plug them with?

I think your solution of replacing the over-axle pipes and removing the OPF matrix will be a very popular solution to get a bit more sound from the exhaust while keeping the PSE functionality. Can't wait to see the finished product.

blackholescion

If the car sounds like that with just the particulate filters removed, then man, that will be easiest mod to uncork sound ever. Sounds really really good with just the OPF deleted.

Rennolazine

Also looking forward to some street HFC headers and some dynos
BTW when you were taking off in that video (valves open) did you hit the rev limiter or does the car do an upshift atuo-blip shifting from 1 to 2? My 991.2 did a throttle blip on 1->2 and it drove me crazy

Soul Performance

We were hoping it too, and as soon as that car started up it was an immediate “Oh Yeah, That’s a Winner” haha.

I have a set of prototype slip on resonated turndown tips up with Dylan and Chris at Bohica Racing to test at Tremblant when the tracks open back up. They’re derived from our 991 GT3 version currently on our website. With luck it should make a notable improvement on the Boxster/Cayman platform as well.

No problemo, happy to help Tom at DSC has been great to work with and I expect this is going to be a very popular new product they’re developing.

That is correct, once the vacuum lines are pulled the PSE button is essentially disabled. It’s always open no matter what you do with the button. You would pull both vacuum lines off so it’s the same on both banks. Can’t recall what our tech used to plug them, could have been some golf tees he stole from Gary’s office, or not haha. I’ll find out next week and let you know

Its definitely a whole lot easier than the 981 generation that’s for sure!

Headers and dynos will come in due course. You know I didn’t really notice it when I was driving, but I’ll keep that in mind and take notice next time we go out to do the videos. Thanks for the insight!

Regards,
John Gaydos

InTgr8r

@Soul Performance
Hi John, great to see the progress on the 718 GT4
Love your downpipe product on my 718 Cayman & look forward to doing business again.

Question on the PSE mufflers.
Do you know if there is any king of merge or crossover between the two banks in that mid section above the diffusion?
Or are the two banks isolated straight back.

Soul Performance

Here’s Bob’s thread I was referring to in my earlier response.

https://rennlist.com/forums/991-gt3-...-gt3-rs-4.html

Thanks very much for the biz on your 718, and for chiming in!

Im taking a scope down the muffler next week to take a peak. Looks like valves open it comes right out the exhaust tip from the over axles with little to no restriction. Not sure on valves closed yet. I’ll try to convince my buddy Lou to let me cut a big window in the factory muffler to see what’s going on there...for science! Slim chance of that happening but who knows haha.

Regards,
John

InTgr8r

FWIW, someone else posted a great idea in another thread.
Disconnect the vac lines and thread an Allen head M6 grub screw (set screw) into the line.
Thread it in far enough so that the vac line can be pushed back onto the valve fitting.

Completely transparent solution and easily reversed.

Sorry, I forget who originally posted this idea.

Soul Performance

Someone get this man a beer!