Main Motorcycle: '07 Black
Join Date: Nov 2008
Location: Prescott, AZ
Stock headers on these bikes are 1 1/2", so a muffler shop should have that size on hand. I'd stick with that. If you're going to run them pretty long, a simple rejet should give you good performance. By using extended pipes of the same size as the headers, you should pick up some marginal backpressure from the snorkel effect.
Please let us know how this turns out. I for one have considered doing the same thing just to have some straights on hand to swap onto the bike when I feel like raising a little hell. It should sound awesome, and with the longer pipes, most of the noise will be behind you as you're tooling down the road.
If you cut the pipes off square, the exhaust projects back and produces more of a booming sound, while doing a slash cut produces a sharper tone, bouncing the sound off the road. If you turn the slash cut out rather than down, the sound projects out, making it louder from the rider's perspective. Slash cuts that face out are a blast in tunnels or under an overpass, but otherwise tend to sound pingy and be annoying on longer rides.
"Cognito Ergo Wrenchum"