I just bought a 24 SIlverado RST 5.3L. Truck had single exhaust. I bought the GM offered Borla upgrade to dual exhaust. Had it installed by the dealer. Left pipe/tip points straight and looks great. Right pipe/tip points about 5 degrees to the left. Service mechanic and manager insist they followed installation instructions and are at a loss on how to fix. Any ideas out there in this forum?