Gonna put headers and new CAT on my Si, to go with HKS, Apex-i exhaust and short ram filter. Don't know if I can pass a smog with the high flow CAT. They're crazy inexpensive on ebay. Around $30 WITH shipping?!? I don't know what's up with them. Any advice? Do they give you more HP? bottom end? Top end? I'm going from a Chevy Small Block 406 to the Civic Si. I'd rather put things on the car that give low end torque as supposed to a top end boost. The car is just to fun to leave stock.


Thanks!

 

Nope. Those are test pipes, they contain no catalyst and your car will, I'm 99% sure, fail.

 

Hmm. So basically it's just a pipe to allow you to take the one that works off?
just extends the pipe?

 

It replaces the constricting Catalytic converter, and thus makes your emissions worse for the environment, but better for performance.

 

Therefore, it does nothing. Will it make the car louder? I don't really want it to do that.

 

just keep the catalytic you have on now. u won't notice a huge difference. i have a gutted cat on my car with a swapped engine and have to get it smogged under the table. i suggest you just stay with your cataytic because the gains with straight through aren't that impressive. that and a hollowed cat or test pipe is a lot louder.

 

NICE! Thanks for the advice. Another question. I have an extra P06 lying around. I was thinking of chipping it. Can you chip a P06, then use it in a Vtech where you'd have a P28?