Yeah...the law is the law but it really does depend on the cop on what happens to you. So it appears that the two state statutes kind of contradict themselves. But neither says you cant modify the exhaust. One says you cant modify the exhaust to be louder then your stock exhaust (which means unless cops are driving around with books that show the db levels of every car ever made this may be hard to prove) and the one says "in no event shall an exhaust system allow noise at a level which exceeds a maximum decibel level to be established by regulation of the Department of Environmental Protection as provided in s. 403.061(13)"
Then a test must be done from 50' away in the center of the lane traveled....lol.
MAN....I'd have to say there going to have a tough time with this one in court. If you get a ticket for this study the statute that they give you the ticket on and you may get lucky. One time I got a speeding ticket and the statute said that non business/non residential roadways in Hillsborough county should have a speed limit set to 55 mph (45 was posted) unless a survey is done to prove it was necessary to reduce the limit, I called dot and got a letter saying a survey was never done and I beat it in court.

Anyway, the point is the law does not say "ANY modification to the exhaust is illegal"

Good luck, have Fun.