Hey everyone I reacently got a dual cam zc installed in my 89 civic. I'm curious as of why do I get backfiring any time I'm over 2,000 rpms and go from coasting(decel) to just getting on the throttle. I didn't notice this until I got a free flowing exhaust. I'm just worried that a low a/f ratio will hurt my new cat. I've done a compression test and it turned (from cyl.1-4) 220 210 211 220. Thanks for any help u can provide.

 

because your exhaust is free flowing.. ITs not a bad thing..