so one of our hire sport 4s cam back making a loud popping noise, after having a good look to see what the issues was it was found firstly that the bolts for the exhaust on the rear cylinder was missing and it has separated, better look at it the lower of the bolts had broken off in the block aswell. pain the back side but not a big deal drill it out and put a new stud back.not the big problem which was when checking on the the other cylinder the exhaust had broken at the start of the cover (bend ) has any body had this happen ? the other thing was that the exhaust heat had melted below the heat shield through to the rear seat, lucky no one was sat there as well as it was lucky that none of the wiring has been damaged but it has been affected by the heat and that it didnot affect the fuel tank.
     

[2015 Z Force 800 53/Trail EPS]

Sounds like whoever was in charge of installing the exhaust at the factory didn't do their job correctly that day. On mine whoever install it tightened the nuts so tight they bent both flanges. Fortunately no leaks or broken studs.