Alright so this is the letter that I got in the mail a while back about how I fought my "modified exhaust" ticket, and I won, it got dismissed. Unfortunately I didn't make a copy of the letter before I sent it off, but here's the letter I got saying that the case was dismissed, and my money refunded. Check it out, you can do it too!! (Side note: I think that I'm going to try to get a copy of that letter to post up what I actually sent.)
If you look in the middle of the first image where it's written in pen "27151a" is the California vehicle code for exhausts.