Judging by the fact you're asking these questions I can already tell you're in over your head. To make it faster, first convert it to a Car, Truck, or Buggy, see the link in my signature for details. At minimal, get rid of the excess unsprung weight of those tires.
A mamba 6800kv with a 2s lipo is more than enough power for these. Anyone that tells you otherwise must not be trying to control it in any way. You need to fine tune your suspension to keep the power to the ground, which will require a lot of patience which will also include keeping the center of gravity low. I recommend installing the stiffer RPM arms and shock towers in place of the stock parts. Next you'll need to focus on your driveline. MIP Superdiffs with factory team carbide diff balls, factory team center drive shaft, and MIP cvd's will make your driveline durable. Do not for one second think you won't rebuild a diff, because they will need constant attention with that kind of power. Once you see the size of the diff balls you'll understand. Properly tuned gear ratios are key to keeping your motor cool. Also remember, things this small break easy. Hitting a curb will certainly equate to a complete rebuild. Doesn't hurt to pick up a RPM bumper.
My old RC18T with 2s lipo / 6800kv Mamba 25a and all said parts installed on half charge and damp pavement. Sorry this is the only video I had, it was much faster on a fresh charge and dry pavement. I also rebuilt my diffs before selling and it made a huge difference. I could have changed my gearing and easily hit 55-60mph.
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