Here is my HPI, so far the only modifications to this car are full bearings, the two speed transmission with O.S. 12 CV-X engine, Graphite Upper Chassis, Graphite rear Brace, Composite brake disk, CVEC Exhaust, X pattern belted racing tires. This car is really competitive. I would really recommend using the O.S. Max CV-X engine, because the HPI motor leaves a little to be desired on the low end side. Using the O.S. carb helps the HPI motor a LOT! Futaba radio with a RCM Shredder micro receiver makes sure the signal gets there. I think this is one of the best cars for the money on the market, and is the only choice for the RCS Racing Team. The 4 wheel drive keeps it going where you want it, and with the new one-way differential for the front, it steers like a roller coaster on rails.