Soul Performance

Aw come on Jeff, you could have said something like...."SOUL uses this approach on all their 996/997/991 Turbo systems, going as far as to additionally utilize a chambered X-Pipe, and Helmholtz resonators on the catless versions of the 996/997 when there is extra space"

But now that I'm done busting your chops haha, yes we tried multiple resonators with and without Helmholtz, with and without valves and different flow paths, piping diameters, etc. No, it did not get the drone where it needs to be from drone sensitive customers. This is not the same as the Turbo model Porsches by a long shot. You probably could put eight resonators in the system and it would still drone more than what we designed haha. We did not rush this exhaust development, we took our time and tried everything we could think of, in multiple ways. To reduce the drone to the level we were comfortable with, along with numerous other variables of sound/tone/pitch, the car needed a muffler in play. And not just any muffler, we had to specifically design our muffler to meet the standards we were looking for. I know you want a non valved exhaust system, a setup properly designed to do what you want when you want it without the valves messing about. If you put this Valved Exhaust System on with our Competition Over Axle Pipes, and run it with the valves open all the time, this is the setup you are looking for based off our exhaust chats this year. Give me a shout when you have some time, we'll chat about it more in depth and maybe I'll convince you to take a leap of faith

Regards,
John Gaydos

lovetoturn

Cleaned up my last post. Thanks for the comments John. We will have that conservation sometime soon.

s2kspyder

Hi John,

Can you please share the before and after dyno plots for your race exhaust?


thanks!

Soul Performance

I look forward to that my friend, I always enjoy our conversations

Sure thing, this is the before/after dyno graph sent to us by Jotech.

Regards,
John Gaydos

usctrojanGT3

Nice power gains for just a catback exhaust. Was it with just the exhaust (resonated or non-resonated)?

Soul Performance

Remember our Race Exhaust deletes huge corks in the exhaust system (the particulate filters) which have very similar characteristics of restriction as cat cores. This is in additional to piping diameter, flow path improvements, etc to improve flow that you would see with a typical catback exhaust development. Though technically our Race Exhaust is a "catback" system, it is doing much more for flow improvement than let's say a catback system for a 981 generation GT4/Spyder. That dyno was with just the replacement of the factory over axle pipes and PSE muffler with our Non Resonated Race Exhaust. There is no notable change in flow or restriction between the resonated and non resonated system, those resonators are literally straight through.

Regards,
John Gaydos

lovetoturn

That video sounds great. True flat-six howl. I am going to listen to it again.

s2kspyder

Thanks John for the prompt response as usual! Great customer service! I am impressed with the plot. I was concerned a little with a lost in mid-range power (at the expense of maximum top end gains) but I see none of that here.
Having said that, if the piping was as short as possible (i.e. without the loop and x-pipe, etc), would there be a reduction of back pressure so the mid range may suffer? If so, the maximum power gains up top would be even greater than 30?

Soul Performance

No problem buddy, I try to be prompt when I can haha. Backpressure is misunderstood by most, and reducing it is only going to help everywhere in the curve. What it really comes down to is scavenging and exhaust velocity. Rather than do a deep dive into this topic myself, Engineering Explained does a superb job getting into the nitty gritty of this in the video below. It is very educational, and definitely put some time aside to really take this in as it's the best introductory explanation of exhaust design and flow I've come across. On that topic, an X-Pipe has a scavenging effect while a straight pipe does not so an X-Pipe creates better exhaust velocity in most applications. We tried a shorter straight piping on this car, and quite frankly even if it performed better than an X-Pipe it sounded Not So Great as you unrestrict more and more flow upstream by ditching the particulate filters and cats. Not merging of the exhaust flow leaves a raw, unrefined, deep, two banks of 3 cylinders kind of sound that is not what we've come to know and love the GT cars for. Blending the exhaust flow with an X-Pipe not only helps with scavenging, but brings that flat 6 smoothness and higher pitch back in play as a huge improvement in sound/tone change.

Best regards,
John Gaydos

Jim Rockford

This just went up. Haven’t watched full video but the sound clip at the beginning sure sounds promising

tigerhonaker

I have watched a lot of the Obsessed Garage videos on the GT4.
Many of his videos are interesting.
They cover everything from him taking delivery, Highly-Detailing It, then his drives in it, then him doing the changes/modifications to it and there are quite a few of those as well as him trying lots of exhaust options.
Worth checking into guys.
Type in "Obsessed Garage GT4" on You-tube.

Terry

Porsche444

If there's one thing I didn't like about the GT4 is the sound, its just a bit whiny. So, after doing research and picking the best in the industry. At startup, you can just hear the difference, gotta be 30-40% louder and once you hit about 4k+ rpm, this car sounds SO DAMN GLORIOUS!!!!

https://soulpp.com/product/porsche-7...er-axle-pipes/

Cant say enough good things about John Gaydos at SOUL, shout out to him and his amazing team, thanks John!!

rahtid

blraider97

m

I agree. I’ve had my OAPs installed for a few weeks now and really like it. Initially I didn’t notice drone but it’s there when the windows are up. With that said, I don’t really care since this is purely a weekend toy and I almost never have anyone in the car with me or a need use the phone. I’m toying with the idea of adding the Soul valves rear section for a more complete sound but honestly I really enjoy the basic OAP set up.

The one thing I have noticed is a higher delta between front tire pressure and rear tire pressure when I’m pushing the car hard on the twisty stuff (no track day yet). Not sure if it is the fact that the OAPs aren’t heat shielded but that would seem to make sense. On average I would say the rears are running 2-3 psi higher when giving it the beans over any extended period. Something I will continue to watch and may have the pipes ceramic coated if I continue to see the trend.

Lastly, I too feel that there is some added performance gain. Not huge but it’s there.

Porsche444

It's odd you mention the heat from OAPs, because my issue is I can't get my tire temps high enough, dunno?