On the Vmax, people drilled the rivets and pulled the end cap off. Drill 3/8" holes between each rivet and repaint the end of the exposed muffer. It sounds better and you lose just a little performance.
Definitely spend the money to rejet after changing the exhaust. Even stock bikes usually benefit from a rejet. It should cost no more than a new set of tires, and the benefits will last as long as you own the bike.
Seriously, I can't emphasize this enough. I built a professional reputation as a mechanical wizard just by correcting customers' modifications.
More power, better throttle response, less risk of catastrophic engine damage, no loud bangs on deceleration. There is no better performance mod for the money.
quiet is good, I put a Holeshot can on my Bandit awhile back but didn't re-jet, above 7k it hit really well but loud, I got tired of the noise and went back stock and sold the H/S on a Suzuki owners web site, I was amazed at how much better the bike ran stock, the H/S worked well at high RPM but I lost grunt in the ranges I run at most on the street. One of the rumors flying around is that the next gen Bandits will be EFI and shaft drive a`la GS11's, other rumors are that they'll do away with the Bandit and import the GSX1400. That would be fun and would compete with the ZRX, as long as they offer a big air/oil cooled 4 I'll be happy.