I've been on a ghost hunt for the last month trying to find the cause of a metallic-y rattle only under load. Car has a stock header and a stock flex but everything else is aftermarket w/ new gaskets, band clamps, and wurth exhaust paste. I've ruled out a leak. The flex pipe is the last thing I can think of. The previous owner did put a hose clamp around it so I'm thinking it's that. Question is for the guys who have replaced their flex. What did your bad flex pipe sound like?