i honestly think its the Rice factor that they look for... i have a civic hatch... fully built and boosted, with a 4inch open down pipe... yes its loud, it sounds like a turbine engine crusing... but i have knock on wood gotten no tickets in it, the only time ive gotten a ticket was back in the day with a ricer apexi n1 canister hooked up to the back, i got pulled over and given a ticket (the muffler wasnt even hooked up... lol. now i have nothing back there to draw attention, and driving in low rpms i just sound like a semi rolling around