When I installed my S & S headers on my 430 its didn't get that much louder, just a little throatier at some points

 

yeah do this. I once had a buddy who spray painted some large mesh foam stuff black kinda like the stuff in a fuel cell and then jammed it in his exhaust right before the inspection place. Thats really bad for your car but its only for like 10 minutes while they inspect it. He even pulled the **** out with a coat hanger in their parking lot. lol