Radar detectors in Texas work off speed not sound.
i dunno about elsewhere.......but here in nj police tend to pull over certain things, more than others. mustangs are one of those to get stopped more often....as are camaros, vipers, vettes, any of the japanese turbo toys...........
oh yea....i've listened to different exhausts for the gt's online. not a single one of them really truly sounds better than stock. they're just louder. it ain't worth the cost to just make it louder. if i could get that sound of the green hot rod that steve mcqueen drove in a certain movie.....that'd be worth it.