Flowmaster Super 40 mufflers

Got 40's on my 318 6pack in the Fury. At 30-ish mph in the neighborhood, the drone is a bit much. I've got 2.5" all the way back with no x or h pipe. Then again, everything is louder when you're topless.... Been on there for 10 years, tho - other than the drone, I love the sound.