How about plugging the exhaust tip on one side and see what it sounds like exiting only threw one side?
It isn't resonance in the metal that can be tuned out by weights or braces in my opinion. It is a noise from the actual exhaust gases/noises. I have a '71 Nova that had straigh pipes when I got it, and it droned awful. It went BLAT BLAT BLAT down the road. Horrible. An H pipe cured it instantly. Then flowmasters made it even better. This is an area of concern for me, I just don't care for 6 banger exhausts for the most part. However, I'm going to put on a Hollywood Deeptone dual manifold to go with my McGurk twin carb intake on a 235 in the ol' '53 5 window. I think I'm going to get the shop to let me listen to it straight, and with several different muffler combos before I get it all tacked together. I bet if you put a rag over one pipe it would stop the drone, just an experiment that would take just a few minutes.
The Jalopy Journal
