There are usually pros and cons for every change you make to a OEM product. The belt is quiet, never needs lubrication and the new ones are rated for the life of the bike. However, chains allow for gearing changes and provide weight savings. Chain technology has come along way. New X-ring style chains provide good longevity and are substantially quieter than the kind you would have found on a dirt bike when we were kids.

In my case, I feel that the chain is the lesser of two evils. In order to run a belt and a 240mm tire, the wheel would have to be offset in the swing arm. I am able to run the wheel in the true center with the chain.

Also, dans03firebolt is correct. It does nothing to increase or decrease power at the crank. It is the delivery of this power to the wheel that changes. Normally the fewer teeth in the rear equals higher top speeds and more teeth gives greater torque.