How do I check my engine for good compression?
Is it bad to costum an exhuast for a n/a or do I need to buy a catback? Is there really a big diff. if I good single or duel?

 

You can use a generic compression tester if you hold the schrader valve open & watch for the high point of the needle bounces.

Only the 86-88's used exhaust backpressure to open the aux ports.
A single only needs one cat or pre-silencer.
A dual sounds cool.

Check out the sound clip link in my sig.