Exhaust Rattle and blowing + Maintenance course

[Dead Eye]

As a guess I'd suggest the gasket is failing between the can and the connection to the pipes / headers. Its not an expensive part and is really easy to check - remove the can is very simple and easy to do, especially with the OEM can. Only the OEM cans seem to have this gasket, all aftermarket systems just use tight fitting metal pipes and a clamp.