I just bought stainless headers ,does any one know what diameter exhaust pipe to use with out losing too much back pressure? 1990 -2.2LX ----Any suggestions on a muffler, medium loud???

If you're talking about a header...I don't know what you're asking.

If your talking about exhaust piping...it depends on which engine. Never punch out your cat.

I re edited my question, thanxs for catching that. I just woke up when i wrote it

Piping size for 2.2 liter N/A = 2.25" or 60mm (for jdm exhaust parts)

Mufflers = Borla, Flowmaster, Magnaflow, etc.