the only motors that pacesetter header fits is the g54b 2.6 and g52b 2.0 - NOT THE g63b 2.0. you either need the dg header on here or get one from austrailia and fix it to fit the US truck. It does make a difference, for one thing it gets ridof the cat in the manifold and allows for a free flow cat if you need to run one. There is a post on here where to get the transdapt adaptor.