so im either gonna go with am HR1 Riot slip on or a Jardine gp-1 slip on for an '03 r6. but here's the question... i know the riot will fit. but if i go with the gp-1, the oldest r6 they make it for is the '06. so would the pipes still be the same diameter or would i have to get an "expansion" piece of exhaust? what other mods would have to be done to make the gp-1 fit? thanks guys!