Hey Josh,
I run Beringer bars, and I've cut about 1 1/4 - 1 1/2" off each side. They're almost too narrow now, I think maybe just an inch off each side would've been fine... Anyway, assuming I DID take an inch and a half of each side, that would suggest my bars are now 22" wide :-\
Narrower feels nicer for bunnyhopping and so on, but less width means less balance for stalls and so on, pretty much, just 'cos there's less leverage...