Hey guys I have an 05 G Coupe 6mt and installed my test pipes about 6 months ago. The check engine light came on after about 20miles and never disappeared since. Last saturday i was driving back from work on the highway and decided to punch the car all the way to red line, and i rarely drive rough. when i came home the light was still on, but the next day when i started the car the CEL was gone. Its been a couple of days already and still no CEL, is there any reason for it not showing. and btw those are megan racing pipes and other bolt ons are headers, exhaust, clutch and flywheel, spacer and intake.
Thanks

 

Maybe you're lucky?

You could also get some newer 3" downpipes w/HFC's, probably better than smaller diameter test pipes. I got them on my TT install, no CEL yet.