Porsche 981 GT4 / Boxster Spyder / Clubsport SOUL Long Tube Street Headers

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: Stock GT4 385hp @7400rpm 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. Overall 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.