You don't want to gear higher with a mod motor to make the car easier to control. With the instant, insane amount of torque that mod brushless motors make, a higher pinion will not really mellow out your bottom end. It will simply make the car faster top speed wise and generate heat. This was different in the brushed days and with 1S.
If I was to make a list in order of importance for the key for controlling fast motors is
1.Boost (and start-end RPM) 2.Turbo 3.End bell Timing 4.Throttle Expo 5.Gear Ratio.