i also wanna try 16/42 but then....after seeing arechin picture...i think better not....i dont want my engine case to blow...ahaks...
arechin...save your money....dont always change sprocket, this machine needs time to absorb the new setup....everytime u swap sprocket...give the machine time to understand... 3-7 days will be great....
as i said, if your bike is oem setup, use 15/39 or 14/36 dont go lower... my 2 cents...
sprocket will not give you alot of power.....carb settings, cams, pistons, exhaust thats are the things that you really have to concentrate if you want extreme power...