I hear a 14T front sprocket will give you an extra low end umph, but it will cost you some high end speed. If you change the chain and rear sprocket you will have to get a speedohealer.
They have some guys at svrider.com forums that have done plenty to gearing if no one else here has, you might want to check out that forum. I hope this isn't advertising, I am just trying to help this guy find his answer. Shan or any other of the mods, please feel free to edit if it is advertising.
2005 Honda CRF88RR - 2007 Honda CBR600RR