I'm sorry but unless you are driving a pro street dragster... no ticket is going to stand without a decibel meter. This is coming from someone who has been a cop. A lawyer would have a field day, the reason law enforcement has the meters is so they can accurately say your car exceeded the legal level.
On to the following, totally legal.
The cop does need a reason to pull you over, but the "talking to" was bull. He can in no way prove you were the car in question. If it continues to be a problem talk to internal affairs at the police department.