This Performance Twin Idler Gear Kit corrects the weakness of the stock setup, by replacing the needle roller bearing and the twin sprocket, to reduce the timing chain friction and stabilizing valve timing. The RPM tolerance of the kit is an amazing 13,000 RPM. The slack side chain guide and tensioner will no longer be needed, as the twin gear does a better job at the same function. Cam spacers are no longer necessary as the kit is adjustable up to 4mm. Choose Anodized Red or Blue, or Polished for the head "slide" plate. The slide plate and sprocket are Chromoly.