Mine's running a 2 1/4" universal slip on with a custom mid pipe (made my local Carline exhaust shop) in stainless.
Total cost was about $300.00 and has a pretty nice note on her- not too loud yet you know it's there.
You can get later model OEM cans that have a slip joint ie some 600's etc but normally the mounting bracket is not suitable.
(Check ebay for Yoshi cans.. A few around ATM cheap with minor scratches etc which can be polished out.)
You want 2 1/4" inlet (57.5mm) universal fit. If you take bike to local exhaust shop a new mid pipe quick and easy to make for a good exhaust fitter particularly if you remove OEM mid/can for them.
Make sure you get a can with a universal type moveable bracket. Ie you can mount anywhere on the muffler body.
Hope it helps
