I am running the mamba comp-x kit. The kit has a 8000kv brushless and a mamba 25 speed controller. the things that i would change to run this are, rear ball diff, steel front axles and a 150 mm wheel base.
On top of that stuff listed i have also upgraded to the penguin 3500rs chassis with the vcs 1/12th rear shock and a hitek 85mg micro servo and dual steering kit.
Castle Creations offer there brushless kits in 4 Different kits.
Sport Mamba-25 and CM-2042 Sport Motor (4200Kv)
Performance Mamba-25 and CM-2054 Performance Motor (5400Kv)
Competition Mamba-25 and CM-2068 Competition Motor (6800Kv)
Competition X Mamba-25 and CM-2080 Competition X Motor (8000Kv)
All of these kits come with the mamba 25 speed controller
The kv rating is the speed of the motor the higher the kv rating the faster the motor.
Here is there web site for more info.
www.castlecreations.com/