i prefer to work from the back when it comes to exhaust for cars with headers, first hang the tailpipes,then install the mufflers and last the headpipes, all headers end up in slightly diferent locations and its impossible for a exhaust company to make a set of headpipes that fit them all,its all about geting most of the system to fit right under the car and then figure out how to make the fronsections fit the headers wich may end at the right or wrong place.