First off, Im new here. I just picked up a 04 tl 6speed. The car has full exhaust... rv-6 precat deletes j pipe and magnaflow catback. A few times so far on a cold start the car gave me a check engine light for random misfire and misfire in pretty much all cylinders. It makes no sense because the car runs smooth as could be with great power.
Someone told me it could be caused by the straight pipe instead of having cats. Is this possible?

 

i don't agree, if anything that would make your car run rich. Which means you have to keep a closer eye on your ignition parts such as plugs and coils..have you checked them yet? if not; go..now. lol and let us know.