I can't find any specs of the pipe diameters. The slip-on I'm looking at is a Gianelli aluminum for a GSX-R 750 '00 - '04. It's a lottery, so it won't cost me anything if I win it. I doubt I'll win though, but it's mostly for fun. What mods are required if it won't fit? I don't have any welding skills, but I know people who can get it done (hopefully).
I believe it should fit with either an offset flange or a offset bend pipe setup. Some like this...
http://pg.photos.yahoo.com/ph/seshadrisrinath/album?.dir=/878b&.src=ph&.tok=phS.e5BBcUk1tpBz
Cool.
Srinath.