there is GSF Racing up in Quebec that does it. seems allright for what i can see on shiftnrace.com. http://forum.shiftnrace.com/viewtopic.php?t=637
I think that pro tech up here in Halifax can do it too, I never seen any banshee's that they have done but they are kickass in the Motocycle industry http://www.protechsusp.com/mods.htm
but shipping to the states is really not that bad, I'm on my 2nd set of US ported cylinders and shipping is 25-30$ each way, about 10$ more that shipping into Canada. but I think its well worth it to spend the extra little bit to get them done by a reputable Banshee guy.