It depends on the judge. You would want to plea "compliance" and show evidence of fixing the exhaust. Most judges will accept it and drop it. Once in a while you'll run into an asshole who won't accept compliance as valid and calls it guilty immediately (true story, I was in court one day where every single technical/equipment violation that was contested with a compliance plea was automatically immediately found guilty and sent to the booth to pay). Do NOT pay the fine if you can avoid it. A lot of times the more tickets you have the more often you'll get pulled. I never got pulled for exhaust for a long time, finally got a ticket for it once, was lazy and paid it. Now I get pulled over for exhaust no matter what car I'm driving, even if it has stock exhaust they still pull me over, and I've also been ticketed for stock exhaust, only because they see I've been ticketed before for it and think it's easy money.