personally i would have 2 say the scorpion from
http://www.b-p-p.com/Mini-T.htm is the fastest and also the cheapest i might add.
you get the motor and adapter plate for 25.00 and your ready 2 RIP

also theirs no brushes 2 change, i hate doing that[:'(].
mine slaps around the BAJA like nothing

and i still get my 20-25+ mins WOT run times.
if you want 2 spend a few bucks more i would get a BL system for around 130.00.
youll get 40+MPH speeds and never have 2 change a brush again lol

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stock electronics are the OEM electronics, meaning all original stuff that came with the car when new.