Currently, I have long-tube headers, 2-1/2" all the way out to the flows and out, dumping at axle. The only points on the car where they are mounted are at the headers, and hanging from a rubber hanger at the back seat bolts. I first started to get drone when I installed the headers, and went 2-1/2" into 18" glaspaks, then exited out the side in front of the rear wheels. It was a mild drone, and it only got worse with the flowmasters. I have always wondered if some of the drone isn't coming from the headers, themselves...
Hey Scott you may have been through this already buy i found a loose brace behind the back seat (you can inspect it from the trunk) the weld had let go and would vibrate just enough to give a resonance.I thought i had a loose exhaust hanger and it took a while to find it was the brace.Just a thought...
Long tubes, back to flowmaster 40's dumped behind the mufflers under car. I do not like flowmasters, they have that tin can rattle to them. Zero drone...Drove an hour at 3500rpm after the rear end gears and it was actually quite quiet....