I have a ITR factory exhaust, and I'm planning on buying a Comptech 4-2-1 header, will I need to get a HI flow cat? Is it worth spending the extra money? BTW I don't race anymore, so I'm not looking to have a heavily moded engine.

 

if that's the case, keep the stock cat. a hi flow cat is only going to add more noise and very little, if any hp with minor mods on your car.

 

you dont need to, but if youve spent money on your exhaust system you might as well finish it off, and if youre not into racing why are you going to spend 400 on a race header?

 

I just wanna to gain street power back. I keep hearing the DC 4-2-1 is crap. I don't want 4-1 cuz clearance problems. I don't want a 2.5 exhaust, I don't like the big mufflers, I like the stock look of th ITR. So there are alot of things that factor..also..I have a truck to work on, and also i'm gonna auto x-cross my Corrado...so I'm trying to keep an even balance on all my projects. So you see my problem.

 

BTW...I'm getting my header for free.

 

the only real reason to get a hi-flo cat if you're not looking for more noise or performance is if the collector is of different size (2.5", etc)

 

keep stock cat or ITr stock cat for the ITR catback
BTW, i have testpipe w/ 02 sensor bung shipped to u for $30

 

well if the other compteh header falls through stick...do you still have yours?

 

The high flow cat works as part of your exhaust system. All three peices work together, not as three seperate parts. Saying "the high flow cat adds minor hp" is inacurate.

With out replacing your cat your exhaust system is bottlenecked and your header and exhaust are not going to be working to their full potential.

Would you put a 2" diamater extention in your 2.25" intake? No, so why do it on your exhaust?

 

I can just go with a 2.25" Hi flow cat?

 

yeah i still have mine but its not for sale until i get my JDM 4-1 which i dont know when that is gonna be. when i do u can get it w/ the hi flow cat i got.
but u can buy my test pipe or get smsp 2.5 cat from him

 

will it bolt up to the ITR exhaust? Is it long enough? and how come there is a 02 bung welded to it? isn't the 02 sensor on the header? sorry so many questions.

 

you dont need the cat --- but it would benefit you to have a hi-flo one for jettin around the streets

 

it will bolt on to the exhaust but will be too short. thats why i suggested ITR cat to go with ur ITR exhaust.
OBD II has 02 sensor in header and cat. OBD I has only in cat