I had exhaust smell in the cab, and was down on power. On the 6.0, Ford uses a bellows on the driver side up pipe, while the passenger side gets a wire mesh flex joint. The drivers side bellows crack, leaking fumes and exhaust pressure that should be spooling up the turbo. The repair shop put on an aftermarket set from Rudy's that has the flex joint on each side. No more smell, and the truck now drives like it should. Plenty of power, and the there is almost no lag before you feel the turbo spool up. The Rudy's pipes are actually a little less than the Ford part and were replaced by pulling the turbo.