i bought my 91 Si about a year ago and didnt think it had any mods to it,a couple of weeks pass and i ran against my friend who has the same car... for some reason i could get him off the line with no sweat... realizing this we pop open the hood... everything looks normal... they both have the same engine....or do they? to the untrained eye..they both were D16a6's but after scraping off the dirt from the block i uncovered what seemed to be two letters..but not numbers... you guessed it ZC... i didnt realized they were identical... now my question is this year is my somg year... will i pass? i have put on an CAI but it has the C.A.R.B sticker... so im not worried about that...but will they bust me for having the ZC? also my car kinda has an idling problem... somebody told me its a miss-fire.. how do i take care of that?