Pro Circuit has been producing motocross performance modifications since 1978 and continues to do so. Pro Circuit was founded in Southern California creating race set-ups primarily for desert racers and has grown to create parts for many offroad racing disciplines, including motocross. Riders like Jeremy McGrath and Ricky Carmichael have ridden for the Pro Circuit team. Known best for their custom-tuned exhaust, Pro Circuit also creates many other motocross parts including clutch covers, linkage arms, graphics kits and more. You can also improve the performance of your ATV with Pro Circuit ATV exhaust. Dennis Kirk brings you the best selection of Pro Circuit parts and accessories for your dirt bike and ATV.