SCX Pro Chassis Audi Speed. SCX have introduced their Pro range of upgrades for you to get the best from your cars and smash those lap times as well as your opponent. You can change gear ratios, add a faster motors, change tyres etc, all will help you win ! Service Items and consumables can also be used on other cars such as Scalextric, Fly, Ninco and Carrera. Superbly presented and packaged as is the whole SCX range.