DEVELOPMENT AND TESTING: By creating a unique application for the 981 platform, we’ve focused on sizing the runners (2”) and collectors correctly to extract maximum power from the 3.8L engine. We chose appropriately sized HJS HD 200 cell catalysts to flow enough power for sustained high RPM use – where the GT4 is at home. Don’t settle for smaller, cheaper catalysts when power and durability is concerned. Third party dyno testing on a Dyno Dynamics dynamometer revealed gains of 30 whp when paired with a tune, with 12 whp gains unlocked by Street Headers alone after the tune had been applied.
CONSTRUCTION: Each header is assembled out of T304L stainless steel and rigorously quality checked in-house. Proven design elements including port matched flanges, smooth radius primary tubing, and collectors that optimize the exhaust flow all work in conjunction to maximize power gains.
HJS CATALYSTS: The highest quality catalytic converters available, known for their industry leading flow and durability. They are efficient enough to meet strict EURO 4 emission standards while still allowing for an increase in flow – all without a check engine light. The HD design uses premium triple foil winding for maximum strength. The brazing stripe is an extra feature in the interest of durability – it prevents the core from moving or experiencing any damage from sustained high horsepower abuse. We use a large and appropriately sized catalyst to allow for maximum gains – no compromises here!
BOLT ON AND GO: Each product is tested in a fixture to ensure perfect fitment. Thorough installation instructions are included in the box for a straightforward install that can be performed by most DIY enthusiasts.
LIFETIME WARRANTY: Enjoy your Soul exhaust components with confidence on both the street and track as they are covered for life! Our team will quickly work with you to resolve any issues or answer any questions that you may have. We cover our HJS catalytic converters with an unprecedented 3 year warranty while the headers themselves are backed by our Lifetime Warranty.
NOTE: This product is not CARB certified and may not be legal for use on emissions controlled vehicles; intended for off road use only
Michael James –
I have had these headers on my GT4 for the last 6 months and couldn’t be happier. The change in exhaust note is a bonus to the extra power and torque the car now makes.
Leave the factory exhaust valves shut and the neighbours won’t hate your choice of car, but open them up in a tunnel, and feel the hairs on the back of your neck stand on end from the fantastic sound coming from just behind your head. The sound emanating from the car at full throttle is incredible and the crackles and pops on overrun are intoxicating!!
Having the extra 33hp at the top 1000revs is good to have on a race track, but the extra torque from 3500rpm up to 6000rpm makes the car much more enjoyable on the road, reducing the need to wring the car’s neck constantly.
The service and advice from the team at Soul Performance Products was a major part of the decision to stick their headers on to my much-loved GT4, a decision I am happy with every time I go for a drive in the car.
Andy Demar –
I spent the whole month contemplating which Sport (catted) headers I should get since I don’t intend to race my car, my first and top choice was Dundon Motorsports Headers since they are local to me and have the best proven performance gain, but you have to pay for top quality products and unfortunately, I didn’t have the budget for their custom Sport headers. The other headers I considered were Cargraphics and Fabspeed. But I ended up with Soul Performance Products not just because they were the least expensive but all the people who had them had very positive things to say so I went with them. I was communicating back and forth with Mike and he was always at disposal to answer any questions I had. They shipped it right away and it took me about a week to receive the headers (PA to WA). The installation guide they provided were simple and I was able to install without much difficulty. The sound didn’t change much (which is a good thing I like the stock sound), maybe a tad bit louder, raspier and drier sound. After the installation of the headers the car felt definitely quicker eliminating much of the lag that bothered me in the first place. I would say with the BMC Air Filter & SoulPP Sport Headers, 3/4 of the lag was gone and I could feel the car pulling harder throughout the rev range. At this point, if you are not as picky as me I think you will be happy with just the Filters and Headers.
mcomet (Rennlist) –
After the install I was of course eager to get the car and experience it. My installer friend is about 45 minutes away from me, so that meant a bit of freeway and some side streets home. Right when starting the car I definitely noticed a bit more noise when turning the key. Not a lot, but enough that I could tell it was more aggressive. That said parking lot speeds and low rpms are basically OEM. There’s not a real noticeable change at slow speeds which is a good thing.
However pulling out and getting on gas down the street with Sport Mode and Exhaust on…. AMAZING. This is what the car should sound like stock. Exactly what I was hoping for. In my opinion this must be what the engineers at Porsche wanted the car to actually sound like. I feel like they must have designed the engine and exhaust, slapped each other on the back in approval, and then been told by managers they had to put on 800 cel cats, thrown up their hands in disgust and gone to eat some bratwurst. The sport cats amplify the already amazing PSE sound back to a fantastic level.
For me personally the volume is basically perfect, maybe slightly on the cusp of entering the loud side. It gives me the “more” that I wanted when at mid to high rpms with the exhaust open. I would say maybe 75-80% of race header volume…which is what I was looking for. If race headers on an open road actually sounds like being inside of a parking garage..this is approaching a similar level but not quite to that full amount. Windows up amazing tone of the PSE and engine. Windows down sounds even louder and I can only imagine how epic it sounds behind the car. I can’t wait to go through a tunnel… If I had to use a word to describe it I would say the exhaust is more “trumpet” like now with loud revs. It’s still the oem sounds but just blasted out more.
In addition I really wanted a smooth pure tone… the Soul headers are definitely doing that. It’s not gritty or coarse like I was worried it might be, and which race headers tend to do as you get fully open flow from the engine. If anything it is smoother and purer than even my OEM setup sounded, or maybe I’m just hearing more of it. But it’s fantastic. You get the Porsche 3.8L sound in spades. All I can say is YES YES YES. This is what you want to be hearing when driving your Porsche.
When cruising on the freeway or bumper to bumper traffic at lower rpms it’s fairly close to stock. With the exhaust open I was getting 76-78 dbA with the windows up/closed. On the gas and higher RPMs with exhaust on and windows up/close it was 87-90 dbA. I did in fact turn OFF the exhaust for a bit, something I never had to do before. That quiets it more on the engine rev side since OEM PSE exhaust is closed anyhow at low rpms. That said you can still have a conversation with someone inside. But I felt like it was marginally louder perhaps. Something to consider if you have to use the car for long journeys.
Even without headers, the stock system has some drone around 2500-2800 rpm…minimal but there. I wouldn’t say that it is worse with the Soul headers, but there is more volume overall… so if you are sensitive or doing a long drive the volume might be a concern. For me I found the overall volume to be right where I wanted it. Loud enough to now hear it and have to maybe turn the radio up a bit more than before…but not so much that it’s overbearing. I took the car to work the other day and honestly I felt like I could easily drive silently just keeping revs down. At 2800 and below it is basically stock. That is sort of my barrier, if I can go to work now and then and not feel self conscious driving. At the same time I definitely had some fun with hard accelerations, down-shifts etc… you WILL get more attention with headers. But I feel like it is the right level for this car.
Being that OEM Cats are 800 cel, Sport Cats are 200cel HJS cats and Race are basically 0 no cats… it makes sense. The sport cats let about 75% more flow or volume through. So it isn’t quite race header insanity but up there.
Oh one other benefit… a bit more “pops” when letting off throttle. The GT4 doesn’t do this much as my 981CS did (which is done by computer). The GT4 doesn’t fake it so you get way less pops with stock setup. But with the new headers I got a handful of nice loud backfires. It is still fairly infrequently … but sounds good when it happens but there are definitely more burbles now overall.
My drive home was mostly traffic even on the freeway. But the car definitely pulled nicely. Not that it was horrible before. After arriving at home I transferred on the Cobb OTS Stage 2 map with my accessport and did a quick drive around town. It was hard for me to register much with the “butt” dyno and just street driving. I will say when I had stage 1 on my Cayman S it was similar… I couldn’t tell a difference from stock to Stage 1…until I got used to it and one day took it off. Then I was like wow I miss all this high end power on the freeway. So I didn’t really expect a big change for me. I’ve only had the GT4 a few months and already running a tune and feeling like the car is already fast enough so I didn’t expect anything.
After taking the car to work and back I definitely notice some more mid range pull. If you are sitting closer to 4k rpm and get on the gas you can often get a bit of shove into the seat. It’s still not a torque monster but it is noticeable a small bit. Honestly I had a hard time registering it the first day or so I had the car. So it may be that the ECU had to adapt or that it’s just harder to tell coming from stage 1. Clearly if you want max gains you’ll be doing race headers, and intakes and a pro-tune. In my case it is solely the headers and tune and 91 octane. The 3.8L GT4 is really perfect for me speed wise. I always want more torque but don’t care about speed. Apparently the way the Soul Headers are designed is for more midrange torque which jives with what I was noticing even if subtly. Low range / low rpm is still pretty anemic, but that’s Porsche NA engines for you.
I asked SoulPP about air filter change / intakes etc. for more gains, they replied that would be more minimal additions vs the headers. Doing a proper ProTune would be the best which makes sense. Overall Cobb Stage 2 with 91 Octane does yield a difference over stock for sure. So I am positive there are gains here. I hope to get a dyno at some point. We can run some numbers off of the Cobb website below…
Just looking at the Cobb Tuning website:
309 ft-lb tq @4750rpm
MAX GAINS 91 oct
GT4 Stage 2 13.19%hp 13.33%tq
Mathematically would be around:
(+50.7 / +41)
435 hp / 350 ft-lb tq
Assuming that Sport Cats are 25% less efficient than race header this would make my stage 2 delta more like for MAX gains:
430hp / 345 ft-lb tq
PEAK GAINS 91 oct
GT4 Stage 2 6.70%hp 5.60% tq
Mathematically would be around:
(+26 / +17)
411 hp / 326 ft-lb tq
Assuming that Sport Cats are 25% less efficient than race header this would make stage 2 delta more like for MAX gains:
407hp / 323 ft-lb tq
So in reality I would venture to say even without a proper dyno my car should be around and probably over 400hp… not a bad place to be for mostly street driving.
The day after getting the car back I decided to do a run up Mt. Hamilton. I actually connect a back road drive from where I live which is about 30-45 minutes, to the actual drive up Mt. Hamilton which is easily another 1.5 hours of twisty and some straight bits of country road and some semi highway bits in-between. It was the hottest day here so far at 107 degrees. I left early and by the time I arrived for the “main” part of the drive the temps had risen from 67 to 84 degrees. I did a mix of driving with windows up, windows cracked and windows down despite the temperature. I hadn’t yet had the GT4 on this road, although I’ve driven it with my other cars. Overall I spent over four hours of actual driving time there and back.
There is no question the Soul Headers were a great choice. Tons of fun volume and sounds. Amazing tone and feel. And apparently there is in fact more power as I seem to be able to get wheel spin in some cases now with second gear at the right rpm. But mostly for me it was about sound. With much of the drive being narrow and some spots of gravel I didn’t push super hard. Except for some areas with good visibility and no one around driving was more moderate. The video below has a number of bits from slow to fast. Be aware the sound from the external mic is a bit “gritty”. That’s not at all what it sounds like in reality from inside the car. It’s loud and aggressive…but has a really good smooth tone. The noise you here is probably due to my microphone and sound placement. At some point I will attempt to get some other video externally and with other devices.
Two big thumbs up for me. Exactly the sound that I wanted and not crazy but definitely “louder”. I have no doubt behind me it must be pretty fun now. Not race header obnoxious but approaching it in a good way. I am pretty sure my wife will hate it, but she already hated the suspension and noise of the GT4 compared to the Cayman S anyways. Cruising which already sort of got on my ears with the stock setup shouldn’t be too bad as it is similar to OEM and it is worth the trade off to get the extra noise for the backroad drives and open exhaust sound. I really use this car for weekend fun…it’s the balance I was looking for. Livable enough for the long part of the drive and exciting for the rest. I also believe I will still pass sound at Laguna Seca by doing the up-shift and half throttle trick one has to do with stock setup since I know other sport cats are able to do that. Or maybe I will get some Laguna Pipes. Mix great customer service and overall for the price and sound and ability to run Stage 2, very very happy with the Soul Sport Cats. If you are in the Bay Area and want to check it out feel free to drop me a PM… Just a happy owner.
NoGaBiker (Rennlist) –
I opted for Soul Long Tube with cats and Softronic tune. My goals: Keep the same sound (tone and timbre) but amp it up a little bit when the binoculars button is pushed. Be able to go into stealth mode in the hood or when I just generally want to keep a lower aural profile. ZERO drone (had it with two different 911 Turbo aftermarket exhausts, it was deafening), eliminate the flat spot in the power delivery, and as a bonus get a few more ponies if it happened, but even if it didn’t I’d be okay with that as it wasn’t my primary objective.
Called up John Gaydos at Soul and had a nice succinct convo with him. That’s who steered me towards Softronic. He was familiar with my shop (the owner runs Soul headers on his 991 GT3) and said it was a good idea to have them order it, which I wanted to do. I placed the order, backlog was about 3 weeks. It all came in and I had it installed and tuned (and plugs replaced while they had the header off) on Thursday.
Soul has delivered exactly what I was looking for. Zero drone, authoritative bark of the flat-six under half or more throttle, docile sounding at low throttle or with the binoculars button not pushed, flat spot absolutely gone, no CELs. The only thing I haven’t confirmed is not tripping sound meters at the local tracks (Road Atlanta, AMP, Barber) but having heard cars that passed there and now this Soul header, I really don’t think it’s going to be a problem.
Fantastic product! I’m just sad I can’t see the things, they’re so beautiful. Where’s that plexiglas engine cover??? (I guess you still couldn’t see them. ) Well done, John and crew!
Alpha.GT4 (Rennlist) –
Finally gotten around to order a set of Soul Street (catted) headers for my 981 GT4. I personally am not a fan of race headers on the street as psychologically I feel de-catted headers end up being a major health hazard (especially if I have my kids around the car) even though it might not be the case
The quality is top notch as many have mentioned on Rennlist. I was cheap/lazy and figured ceramic coating/additional heat shields aren’t entirely necessary for what I do with my car.
The only “mod” I have on the car is a Softronic tune from a few weeks ago, and then I added these headers along with some K&N filters as the engine air filter was starting to look bad. These headers definitely enhanced throttle response (perhaps the K&Ns might have added to that marginally as well). The Softronic tune made things nicer for sure, and I would say these headers kinda added something very similar to that on top of the tune. The sound coming out from the back of the car is a tad louder than stock from what I noticed when going 80% on the throttle. Didn’t get a chance to go full WOT as streets are still kinda wet (it’s been non-stop raining for >1 month already), and my car’s still riding on 6-year old Cup 2s (which surprisingly are still feeling “ok” once warmed up). I didn’t notice any more or less burbles coming out of the exhaust after headers are in, while the Softronic tune actually reduced burbles my car got. One thing I noticed is that in the first 15km or so of driving is that the engine wasn’t running very smooth when I was crawling at very low speeds in 1st and 2nd gear (say 1200rpm-ish). The engine revs were a little unstable, and the car would end up bucking a bit. I suppose the ECU is adapting to the newer readings. However, that kinda went away after 15km or so of driving. As much as it’s a bit of cliche, I would say Softronic tune + Soul headers definitely suits anyone looking for an OEM+ setup. I’m only looking to get a bit of smoother and better response on the car, as well as a notch up in volume. I would say these really did the job for me. So for anyone on the fence but got the budget to spare, I would highly recommend this combo.
Feezy (Rennlist) –
I have a 981 Spyder that’s all stock, and a second one that I have modified.
The second one started with a Soul valved exhaust which I was unsure about until I took delivery. I love the OEM PSE and didn’t think I would care for anything louder. After taking delivery and driving the car the Soul valved exhaust seemed to be be basically a PSE turned up to 11. It had a little bit more bark when the valves opened up but nothing outrageous. I felt like all the low end burbles were more significant and happened with more regularity, specifically at low rpm off throttle points. It was a little bit much, but not the end of the world. I quickly fell in love with it. After driving it a few months I decided to take the plunge and purchase the Soul street headers with the HFCs and add a Softronic tune to go along with it.
After installing the headers I was a bit surprised at how quiet the car still was. Warmed it up with several trips around the block, nothing of any speed or RPMs, revved it a little bit. Got it back on the lift to listen and check for any exhaust leaks. It wasn’t until I got out on the freeway and drove the car to the point that the valves opened up that I heard the full extent of what I had done. It sounds glorious, but it’s not what I would call quiet. I’m a fan of low key tame exhausts, and this is not that. There is no drone, and it’s perfectly livable when you are driving the car like a normal human being, but when you get after it everyone knows. I keep going back and forth on if it’s too loud or not, I don’t really need or want attention (I say that with a bright red Spyder), but holy **** the car sounds good. I’ve heard it standing behind it while my neighbor revved it up to hear it, it really is a fantastic sound and tone. It’s just a touch loud.
Drive both cars back to back, the biggest thing that stands out to me with the with the Soul exhaust & headers versus completely stock is the valves closed section. On both set ups when the vales are open it makes a lot of noise, the full Soul set up is several levels above the OEM car. It’s the valves closed around town driving that really stands out in the Soul car. While it’s relatively quiet and refined with no drone, there is absolutely more noise there than the stock car. It’s not obnoxious or detrimental to the experience, but it’s noticeable. When I drive the blue one it feels very under the radar and stealthy by comparison. All that being said I’m so happy with the Soul combo I hardly find myself reaching for the keys to the blue one these days when I want to take a car out. It’s about as loud as I would want a street car to be and it sounds exceptional. Seriously. The car now sounds like it looks.