For the first time in recent memory, I loaded about 600 lbs of driver, passenger & cargo weight into my 1987 744 turbo. The exhaust pipe suddenly started banging on something when the engine was at low RPMs (ie. sitting at a red light with the auto trans in drive). My 220 lb friend stepped out of the front passenger seat, and the banging immediately ceased (ie. about 400 lbs of load in the car at that point).

Took it into an exhaust shop, where they replaced a couple of broken hangars (one at the very back of the muffler, behind the plastic splash cover under the back bumper, and another about the middle of the underside of the car). This seemed to clear it up with the trans in drive, although in reverse it rattled a bit at idle speed. Mechanic kicked the tail pipe "pigtail" end a bit to get the exhaust to move after the hangar replacement, but no banging noise could be heard when he did this.

Up on the hoist, the car's suspension is unloaded, so it wasn't possible to pinpoint the interference point.

After the hangar replacement, I then took on a total of about 750 lbs of driver, passenger and cargo into the car, and the exhaust started banging like hell regardless of engine RPM, vehicle speed, or what gear the auto trans was in. I abandoned the trip after 2 blocks of the infernal banging, and we switched to another vehicle in despair, a USA-built car for USA-sized passengers.

So can anyone pinpoint where this exhaust pipe banging is likely to be happening? Car has brand new Boge gas shocks in the rear and gas struts in front, and it does not sag on its suspension when unloaded. Apparently all exhaust hangars are good at this point, too.

Ideas?