Great that you are trying it, but I suspect it will be a lot of work for nothing. When I had my old 260bhp Caterham, I removed the rather large Cat, and replaced it with a section of straight through pipe, and have to say, that apart from looking much better, there was no discernable change in exhasut note or noise, nor did I notice any HP gain in day to day driving.
I probably won't bother, I quite like the volume and quality of the exhaust noise just as it is. That's at least one thing I'm happy with!
