ok cool..yea i would like to add some teeth to see what happens..the motor is a 540 brushless 3300kv.
I think it's important to point out here, that we're talking about a drift car. Ph, your info is spot on, but less applicable to drifting. The thing is that in drifting, you want a wide range of wheel speeds, slow with little trigger, for fine tight work, and at the top very very fast, for very sideways sweepers and making corrections when necessary. The wider the range in the middle, the more wheel speeds are available to you. The smaller the range in the middle, the less overall control, but changes in wheel speed with trigger application will be less exaggerated and easier to control. Therefore, you want average to tall gearing, since the lack of torque on acceleration is irrelevant on drift tires, but then you have to consider the rev range of your motor, do you know how many kv it is? To be honest, you're probably best trying to get something going drift-wise using the stock gearing and motor, then see what happens when you add a few teeth to the stock gearing. If I were you I wouldn't be looking to take teeth away, it'll just give you a smaller range of wheel speeds to work with for your drifting. Keep an eye on motor temperatures too, though they aren't usually an issue with drifiting as current draw is low on low traction tires, though motor speeds will be high, so watch out. If you are seeing high temps then consider dropping a few teeth off the pinion, or changing the motor for one with lower kv and higher efficiency.