Programmable CDI For the Yamaha YZ450f & YZ250F.Choose between high spark energy for the trail and even higher for racing. Switch timing curves on the fly. Plugs in to the factory harness. Laptop programmable timming curves & rev limits with optional programming kit. Tear through the corners, fly over the triples and jam down the straights like never before with MSD's new Programmable CD Ignition for the YZ platform. The MSD unit is a direct replacement for the factory ignition module and delivers increased spark voltage and energy to fire up performance. MSD provides 10 different timing curves from mild to wild that you can choose with the twist of a dial. For optimum control over changing track conditions you can easily change the ignition timing curve on the fly! There is also an optional Programming Kit, PN 4220, that lets you connect your bike to a PC so you can coax more power through advanced timing adjustments. Think of the way you could manipulate the timing to help put the power band exactly where you need it for certain tracks and conditions.