klapamos

Hey all,

So i"m considering running a SC on my 2001 S in the future. The car has a ACT pressure plate, AP2 retainers, and BANJO bolt upgrade so its good to go when I'm ready to SC. My concern is that I notice most people use a test pipe with a FI set up. I've heard a cat converter can go bad quickly with FI and mess up your tune. I want to stay legal and use a OEM cat or HFC. I don't want to run any crazy PSI 5-6 should be fine. Would using a cat converter be an issue?

steven975

I've been running FI at 6psi for over 5 years, and my OEM cat is fine.

klapamos

You running a SC or turbo? We are both in Fairfax county . Nice to hear no issues with the OEM cat!

pwrinxs

I've been using a Berk HFC at 8psi for 3-4 years without issue. I'm running an SOS2 SC.

riceball777

You should be fine with a cat at that power level but I would advise against it. The point of boosting you car is to make more power but the cat is one of the worst thing you can have for making power and it's also one of the cheapest mode you can do. Chances are if your boosted your not going to be smog legal anyway.

joes sled 2000

I am supercharged and run the oem cat . Have done so for over 60k without issue . It does cost some power but i think it's worth it . No smell from the exhaust is a huge benefit in my opinion .

MARK AUS S2K

Stupid question but would a 70mm OR 3inch Hi-Flow CAT bolt up to a 63mm exhaust?
You would think this would help the flow a lot.

beechx1

What boost level/power are you at? Do you track your car with the OEM cat?

Chuck S

Use a 63.5mm high flow cat.

Everything I've read here indicated a 3" (70mm) pipe (cat or delete) in the middle of a 2.5" exhaust system disrupts gas flow and robs power. The header is about 57.5mm and dumping that into a big pipe and then constraining it again at the exhaust apparently sets up harmonics or other stuff I don't understand.

Look for "Gernby-san's" (just Gernby) posts from a few years ago. He did lots of research.

-- Chuck

d16tof22

You'll be fine with a stock or HF cat. I have a 63mm cat and stock exhaust and the car is decent. The car doesn't smell at all like un-burnt gas like with a test pipe, so my wife will gladly ride with me without complaining. It also seems to run very clean and has passed emissions a few times now with this setup.

The power numbers in my profile are a bit outdated; it made 396whp and around 260-270lb-ft on the ptuning dyno at around 15psi, which is plenty safe on a centrifugal supercharger.