I am running catless pipes on my 997.2TT and there is an awful lot of brown soot on the rear bumper. I clean it every 2 days which is becoming a hassle. I also have a 200 sport cat which I was debating on installing to eliminate this problem. The question I have for those who had both; aside from the sound, how much performance gain will I loose by switching to the sport cat? Will it be noticeable? Less boost? Ill wait to hear from some of you before I make the switch

 

I run 200 cell FVD half the year, and catless the other half for track days, etc.
I have a black car so I don't notice too much visible soot but I can smell it at idle.

The sound is obviously more raw catless and should allow for 10-15 HP depending on tune. Your 200 cell cats will eliminate any soot and smog odor.
I'm thinking of 100 cell cats. I feel they're the best compromise. Hope this helps.

-Gus Technik

 

Thanks for your reply...much needed info. I think I am going to install the 200 cat cell. Today I took the car into the dealership and they said the P2099 CEL code was related to the catless pipe. Don't know why this would be since I have the mini 02 extenders. I hope I don't loose too much performance but once I get the tune I am sure I'll be happy.

 

Even the 02 sensor extenders are not enough if you're cat free. You're tune has to account for the catless exhaust to prevent CE light and codes..

 

I had been driving catless for about a year and just put the 200cell cats back on. Apart from the smell being gone I also noticed that the car is much quieter now. The hissing/shrieking of the turbos spooling up was nice in the catless car, and going under a tunnel with both windows down and giving it a little gas was almost a religious experience, the car sounded like a racecar. I haven't tried the tunnel thing yet with the cats on so it may still sound good.

As far as performance, I'd say that with the cats it's a bit smoother (both use a mafless tune) and the butt dyno says the power comes on earlier WITH the cats. I'll do a datalog to check the "load" and also a pbox run for 100-200km/hr and see what changes with the cats in place (everything else stayed the same, apart from springs and sways).

 

I decided to remove the catless pipe in favor of the 200 sport cats. The main reason was the CEL, gas fume smell, and the brown soot on the rear bumper. Before the swap I asked a local custom exhaust shop what he thought about the sport cat that I was planning on installing. He was very amazed at the quality of the tig weld and the large open cells. Not sure if it is 100 or 200 but it is night and day different than the OEM. Anyway, my initial concerns were power loss and noise reduction; both I didn't want to lose. The install took a quick 1 hour since the bolts were easily accessible since both the catless pipe and the new cat was not as large as the OEM. After the install I started the car...wow!, the sound is amazing. It is still as loud but not so raspy, more tame sounding. Hard to describe. As far as the power... I feel the car is more linear with the turbo's coming on sooner and not so much of a burst. I really couldn't tell from my butt dyno any power loss. I am sure there might be a 5hp difference on a dyno. I however did dyno my car before the exhaust install. It recorded 444HP (wcf) and with the sport car and xpipe, I managed 486HP (wcf). All in all, I am happy with this mod and am very happy with the sound and performance. I am working on a quick video of the sound.