Specifically made to fit Viper V1™ and BSRT G3-R cars. Medium chassis are usually the best for all Level 10 magnet cars for road racing. A stiff chassis is best for drag racing. It is recommend that you run firm slip-on tires such as Super Tires in compound "B" on a quality aftermarket hub. An all Level 10 road racing car can run 2.8, 2.5, and 2.4 ohm armatures. Level 10 motor magnets and Level 25 traction magnets can be used with the 2.5 Ohm NSX armature for road racing.