Buy here: http://www.speedwaymotors.com/Turbospoke,50683.html
Turbospoke is a complete exhaust system that fits to any bike and makes it look and sound just like a real dirt bike. Turbospoke is based on the old 'baseball-card-in-the-spokes' concept, brought right up to date. The realistic engine sounds are created using long lasting plastic cards, a clever sound chamber and an awesome megaphone exhaust pipe which really amplifies the sound.