Competition - WC S7ii - make sure you are sponsored for the parts !
Fun / light competition - OS V-Spec - Cheap parts and easily available.
Novarossi - Medium to High parts price - serious competition.
Why ? Off Roading is a very high maintainence sport. Requires a lot of replacments parts almost every race -- both for the cars and the Engine.
If you are as unlucky as me !! you drop off your filter while racing - you loose the engine - flat out...as the sand S#r@w$ up every single bit and pc of the inside. Happened to me twice now.