Be aware that some servo's move the other way up than others, that is why transmitters do have servo reverse, to get every servo moving in the right way.
With a Nikko electric car (solid 1 piece electronics) we came to the conclusion the ESC was working better in reverse but without a servo reverse option I had to drive otherwise with the pistol grip transmitter. It was easy to use to.
Some oldies are still driving reversed because they have learned in that way back then there was no reverse option......
Speed is only fiction but a 130+km/h MRS4 is for real.