Bigger Front Sprocket

A 1 tooth change on the front is equal to about a 3.5 on the rear........big difference. Countershaft sprockets are fairly cheap, I'd go just 1 tooth on the front and see what you think.......chain will probably work.

Whats your rear sprocket , stock is like 47ish. so stock is sprocket ratio is 3.35
your new ratio would be with the 15 at 3.133 for a ~ 6.5% toward top speed
and with the 16 it would be 2.94 for ~ 12.25% increase to top speed

so you would gain top end like mad with the 16 , but at the same time you would be losing that same percentage on the bottom end, thats alot , If I were you I would go to the 15 and try it, you would be making a drastic change going to the 16.
Just wanted to show off the math involved
Lok

I may be wrong, but I dont think you'll find a 16?

Stock gearing is 14/47
Countershaft sprockets are available 11-16 tooth.