Hey all,

I've had my FI HFC's for about 10K miles now and love em. But when I go JWT TT, I was wondering if it makes sense to keep em or go with test pipes instead? My biggest gripe about test pipes is the rasp/noise factor but I've heard turbo'd cars have less exhaust noise...so do I keep the FI HFC's or go with the TP's?

What are you guys doin'?

Thanks,
B

High flow cats are legal where test pipes are not. So that makes me say stick with HFC's! Performancewise most people say TP's.

what the hell are you talking about? Test Pipes are legal in 0 states in the U.S. HFC's are.

Stick with the HFC's until you blow one out. Then switch to test pipes. Not sure if you will need test pipes. Most can safely run HFC's.

Cool, guess I'll keep using the HFC's for now. If they ever blow out I could consider the TP's...

How's the noise with TP's and a twin-turbo setup?

Removing/replacing functional OEM cat's pre 50,000 miles is against federal law, even if you replace then with HFC's--you should know that future counselor.

BTW, are you attending TJSL? I went there as a 1L and graduated from Chicago-Kent.

I run test pipes with a Stillen true dual exhaust on my 03 coupe with a JWT TT kit no rasp no drone its fairly quiet now (it was louder before the TT kit with OEM cats and Stillen exhaust).

Nice! I've got the Stillen true dual exhaust too. Looks like test pipes might be in my future after the JWT TT upgrade!

How much HP gain is it with the test pipes vs. HFC's?

**** face reread my post a couple of times before you start calling me out. I said that HFC were legal and Test pipes are not.

Is it 50,000 or 60,000?

Nice idea...wonder if anyone else here's done this.

First off...you have to figure out what whp you want to achieve before doing anything. If you are staying below 500whp....stay with the HFC...below 400whp..you can stay with the stock ones.

Above 500whp you are going to need test pipes to have the turbo's flow as free as possible.

I am running over 600whp with the JWT 700BB and I have the test pipes. No raspy sound here.

How do you pass emissions? Do you switch out the test pipes for the emissions test?

Yeah originally I was planning to do the JWT 530BB set but someone said I should just get the 700BB and have it boost controlled so it's safe for my stock G engine. So the HFC's are probably good for now. If I do go with the 700BB kit, and want to push past 450rwhp I guess I'd need to build my engine. Either way it sounds like I can keep the HFC until I decide to build up my engine to take full advantage of the 700BB kit (like you!)....