Never heard of going to a 16 and I'm not sure there is enough room (chain could hit the swing arm or engine case) so maybe change the rear sprocket. At 16/40 your chain/wheel ratio is 2.5 (stock, 15/40 is 2.67). IMHO they are geared to high out of the box and if you went w/ 16/40 you would need to be going about 90 mph in sixth just to get into the power band. I'm at 14/39 which is a 2.79 ratio. 15/39 is 2.6, 15/38 is 2.53.