Purekoryo

I know there is a limited amount info on the forum regarding the impressions of sport cats alone and then headers + spot cats.

I have a 991.2 GTS PDK with RAS and PDCC, started completely stock.

1. First installed SOUL sport cats:

- Didn’t sound louder right after installation.

- After about 7-10 start/stop cycles and 75 a 100 miles, the sound became noticeably louder. More crackles and pop and increased the sound by around 30% over stock.

- Didn’t feel much power gains in the beginning but after 100 miles, definitely felt faster from mid to high range. It does feel like a 15 whp gain (my *** has been calibrated by 20+ years of modding 30+ cars, doing similar mods and beyond)

- Turbo AND throttle response has been greatly improved.

2. Next up was the installation of fabspeed headers, new spark plugs, and BMC filters. (Car has 26K miles).

- As soon as I got on the road, it felt like I may have lost some power especially low to mid range.

- For some reason it also sounded more muffled.

- That same day/night I disconnected the battery overnight and plugged back in the next morning.

- Started it up and let it idle for about 5 minutes. Just something I’ve done in cars before and worked on some. Felt like I may have gained a little more power back.

- I then intentionally drove it hard, cooled down, stopped the engine and started up, rinse and repeat about 4-5 times. Again MAYBE a little more l power back?

- Day 3: It’s coming alive now. Definitely felt power gains in the higher end. Got most of low to mid range back.

- Also noticed even more throttle / turbo response.

- Still felt like somehow the power was being held back down low to mid range.

- Just out of curiosity, I turned the PSM completely off ( mind you, traction control light never flickered beforehand):

Damn. She pulls hard now! Due to the extra power gain and lack of traction, the ecu was holding power back. The weird thing is that the traction control light never came on and I never really felt wheels spinning. I guess that’s how seamless/good the PSM is on these cars.
Now if I start from 3K rpm roll in first gear and floor it, it’s spin city all the way to 2nd gear.

The headers didn’t make that much difference in sound though. Maybe a tad louder and deeper tone.

I didn’t do a 0-60 before and after but did use my g meter. Right after the sport cat and headers, it was reading 0.91. After 100 miles and turning PSM completely off, it was reading 0.94. Not scientifically precise, but good enough and definitely felt that increase.

Again, based on years of modding cars, this legitimately feels like a 25-30 whp gain from stock.

Very happy with the gains. So folks who do not feel anything from one or both of these mods immediately after installation, be patient and drive normally and do WOT pulls for the first 100 miles AND make sure the engine has cycled at least 10 times.

DonsBolt

if you could choose just one, which would you do?
reading your post I am leaning towards the cats

NJ991

Ok, this is exactly what I wanted to hear about. I also have a 991.2 GTS, but a manual. I was thinking about going the route you have, with sport cats and headers, but I only wanted to to change/enhance the tone of the exhaust. To me, it sounds like there is not much of a difference. I like the fact that you reported back that throttle response has increased with just the sport cats. A lot of people have claimed that. I’m just wondering if it’s worth spending 5k on the hardware to enhance the exhaust note. Don’t want to jack your thread, but would love to get an honest response to the overall sound with these two mods.

Purekoryo

Definitely the cats. In terms of sound, response, power, and $, cats are about 1.5 times better.

Shanh81

good to hear. I just got my soul cats and also ordered the DSC controller for my GTS. Excited to install these and feel the difference

Yojeffo

Be prepared.. The turbo whistle gets real loud in Sport and more in Sport Plus

Purekoryo

Overall the sound with both is addictive. Much more different than stock. I love downshifting when coming to a stop just to hear it. The flat 6 howl is more pronounced but with a bit more metallic sound. Taking off normally from a dead stop has a hint of old school Porsche with a turbo whistle.

Having said all that, I bought the sport cat new and headers used close to half the price. At that price it’s well worth it. But $5K total is a big maybe. I’d say $4K tops within the Porsche world. Man that used to be an entire turbo kit price for my four bangers back in the day!

Purekoryo

I don’t think it’s THAT loud. Taking off normally from a dead stop is when you hear it the most. After that I mostly hear the motor.

NJ991

lol, exactly. 4-5k could get you a decent upgrade on a few things or a kit. Let me ask you this. Which made the most change in exhaust note, the sport cats alone, or adding the headers to your sport cats?

B Russ

I have Soul cats on my 17-4S, to me they are quite loud in sport mode and as said above the turbo whistle is very noticeable. I have found my self turning off PSE on longer rides.
Sorry for the wind noise,

Shanh81

thanks for sharing. Considering the road noise particularly in my 4 GTS the sound might be a welcomed sound

Purekoryo

sport cats alone.

KWP1911

My brother and I just installed my Soul cats yesterday. Immediately noticed the greater turbo sound on the drive home. Sound is a little deeper, but hoping it gets louder over time like the OP suggests.

LWG

Great info. Ive had the Soul sport cats for a few months and it was the best mod so far. I am adding on headers soon and will report my findings.

Purekoryo

Will get louder and more powerful. Make sure you cycle the car and not just one or two long drive and expect gains.

I think what the ecu does it learn (closed loop feedback) during the drive and then with ignition off for a little while and back on, it uses what it learned and goes through the loop again and again.