I was mearly talking traction.. he will get more torque to the ground cause of the small diameter tire, yes. but.. what does he need it for? stock diameter tires have difficulty keeping traction with how much torque is going to the ground, so with that small tire he's gonna have to go really easy on the launches and that I'm guessing will negate any benifites he's gonna get from the lower gear ratio.

now what would be best in my opinion is to go with a smaller diameter tire.. and go with a much much smaller diameter wheel.. so you could keep a good sized sidewall and have the small overall ratio cause of the smaller tire.. but that might be hard to do depending on how large the front brakes are.