Ok so i got a tune done after I installed my cam. My car was just cam only 7.4 pushrods, .650 dual springs, titanium ret etc, msd wires, tr6 plugs, cai, catless mids, and a catback. Now I installed kooks lt's with 3in catless mids and my corsa catback. Now the car is backfiring at idle sometimes and kinda backfires on the go sometimes. under throttle it acts like it wants to go and sometimes gets sluggish. Is this because of my longtube install and not retuning it. Plugs, wires, coils??? Help? Also I have brand new 02's. But under wot it sometimes backfires then chugs and then goes. Sometimes it's fine. It backfires at idle less now that I closed the leak from mids to cats...I do notice that sometimes to fire it up i have feather the throttle after it starts, then it will idle fine. Seemed like idle air problem there. I also noticed it seems like it smells really rich atm...

 

Unless it is throwing some specific code, or codes, it sounds tune-related.

 

Ok ya, I was figuring those Lt's are adding to much exhaust flow for my tune.

 

tune related, i had the same issue on one of my old ls drift cars after doing a different exhaust setup