i have a 90 civic Si with a b16a. I live where there realy is no exhaust restrictions so whats the most basic exhaust setup i could use? what I mean is do I need to have a cat and a muffler or are those something i need for performance? can i just run straight pipe from the header?

 

I live in VA where's there's no smog testing and really no exhaust restrictions either but in order to get inspected you have to have a cat and muffler. I don't know what it's like in AZ but if you run a straight pipe straight from your downpipe it'll be loud as hell......plus if you're running a N/A you want some back pressure. Try looking up your inspection laws in your state is what I would first do.

 

Straight pipe with some type of resonator.

 

i have a 91 hatch with a b16a2. type r replica header, and i have a full welded system. no cat, but resonator

 

I live in CA and I replaced my CAT with a down pipe and no muffler, I just put the muff back on for smog.