You might get 1 or 2 more mph by adjusting the toe. Ideally...the front wheels should be parallel with the chassis when moving forward. Toe out creates drag scrubbing the tires and limits steering. Toe in creates oversteer, and to much of it can create drag as well.
I have an upgraded mine at all. I've had it for a couple months. I've got a big shredded way and it's really smooth. I've got mine clocked at 51 with all the stock stuff on it
Don't think smooth ground had much to do with it. The more times your pinnion goes round to make the spur gear go , your car will go faster but put more load on motor and battery. Less run time also. Not saying not to make pinnion bigger and spur smaller. Just have it all in mind and get a temp gun.
