Throw those stupid flowmasters in the scrap heap. Buy a set of "sonic turbo" mufflers. I have a pair of them on my Charger in 2.5 inch diameter. It idles with a small throaty rumble at an idle. But blip the throttle and everyone knows it is not a 318. Going down the road it is quiet enough to hear the Eddy 750 drinking dinosaurs at a nice rate.