For gearing for RC, you should never have it be 1:1. That's way too fast for speed and way too little torque, especially for a Monster Truck, try a way smaller pinion and a bigger spur to have a 4:1 or even 5:1 gear ratio instead of the 1:1 with 6,000 rpm. It should better your acceleration and increase your torque...then again, I don't know much about engines, I race electric onroads...
Also, this isn't an RC Forum. You should've gone to
www.rc411.com instead or someplace else like that.