i currently have a hpi rs4 car with a new head for lower compression header and exhaust on it 2 speed tranny all new belts and new bele tensioners new clutch k&n mini filter bigger carb stainless fuel filter and it all resides under an gsx eclipse body. now all i need is a new motor cause this one is gone hpi has a mini bottle for the cars which i had on at one time all it does is trick the motor into thinking it has more compression well i flipped the fucking car and the battery pack flew out and by the time i got to the car it had been running at WOT for way to long and the motor was toast. i hope to get a new motor soon so i can see the full potential of the 2-speed tranny.