[aa909]

Thanks Jay, so it's the big power causing the chattering pipes. Only happens during engine braking above 3K rpm though, never in neutral or under acceleration.

I moved the pipes with my foot as you described and even tapped the mufflers with a rubber mallet and they sound uniform throughout, nothing noticeably loose or rattling about. Heat shields are secure, won't budge when I try to turn them. So I wonder if there's a better way to secure the side pipes than the rubber grommet or if I should consider upgrading the pipes to something that can better handle the ponies. Appreciate feedback from folks on these options