If you wish to maintain the stock 108 link chain (and the stock 13T front sprocket), then your limitations are based on how much shorter you are willing to make your wheelbase and whether there is enough axle adjustment.
50T = 1.2" shorter
49T = 1.03"
48T = 0.85"
47T = 0.68"
46T = 0.51"
45T = 0.34"
Shorter wheelbases yield quicker handling at the expense of stability.
Personally, I wouldn't go any larger than 46T on the stock chain.