Your power won't change but your performance will depending on the tire you choose it will be heavier than the stock tire. I have a thread in the builds section about putting 30" Cryptid tires on my machine and the increase in rotating weight was huge resulting in me using low range more to reduce the chance of belt slip etc. If you ride on fairly level terrain you can get by without other changes.
EPI has a clutch kit that I installed and would recommend if you ride in deeper and steeper conditions, it allows your engine RPM to increase quicker after engagement all the way to the top end resulting in a bit more top end (which you tend to lose with heavier tires) and less belt slippage. IMO
I have 32's on Bear.... No considerable difference... many here are running 30's... shouldn't be an issue. Although like Andy said, clutching may be your next move...