I guess I'm confused as to your questions about modifying the SR1 motors, then? Sounds like you are gung-ho about the XP (and I agree, it's a great machine - I have a long-term loaner right now, actually). The SR1 isn't even in the same class as the XP, so not really understanding your direction with this thread, unless it's to champion the Polaris and talk down the SR1s?
PS - While the XP's are great and all, I believe a DSR1 just overalled the last BITD UTV race by about 20 minutes, so they aren't outdated just yet.
Im interested in hearing about this cam that you mention. I dont race my R1 Rhino nor do I ever plan to...however I am always open to the idea of more power...and torque.
I know the SR1 for short course is a spec all stock motor class. but on the other hand, the desert racers it is cc based only I believe, so this is where Crower and others could up the power with stock yamaha parts and be legal.
So for Dan, you really should clarify which type of racing your talking about.
BTW the kawis own 4x4 short course so far. but KOH and Worcs races the XP has reigned on top mostly.