OK, so you are saying that you want fast. How fast do you want/need to go? What does your brother have? An RC10 what?

For a super fast setup that's pretty easy and inexpensive, go with a 4-tec then figure out the greatest number of cells that it will fit and then get the Mamba Max motor that will turn the greatest number of rpms on that number of cells. Within the Mamba Max line, for 4S the 4600 would be the fastest, for 3S the 5700 would be fastest, and for 2S the 7700 would be the fastest.

If you go with an off road vehicle like an RC10B4 or RC10T4, you could run a 4S lipo pack with a 4600 motor and that will get you easily in excess of 60 mph. The advantage of running an off road vehicle is that they have more ground clearance. You will have to take measures to keep the vehicle from taking flight. I used wings on the front and back of my T4 to keep it on the ground at speed.