With all this exhaust talk I thought I'd ask a question that I've been pondering for a while. Has anyone seen or done the following: fit a full set of working sidepipes and for rego purposes, have an interchangeable section that diverts the active part of the pipe back under the car in front of the rear wheel?
Assuming you could get adequate ground clearance under the chassis rail behind the door, you would then be able to fit another muffler or resonator prior to exiting at the rear. Noise problem solved, meets all local rules as far as where the pipes exit, no need for special headers that are a compromise on design when the proper sidepipes are fitted, or discarded altogether.
Sorry for hijacking this thread, but I thought while we're on the topic...