Also watch ebay for a spacer. I've seen one popping up on there off and on. There's a thread on the M1R about spacers, different sizes, and their benefits. There was a guy over there making them but I don't think he makes them any longer. They also pop up on there for sale. Also if you run a spacer you have to modify your rear shaker bracket or raise the front of your shaker so it sits flat. I drilled new holes in the rear bracket to put it back to the stock location. I think I have a 3/8 inch spacer. (1/2 inch with the extra gasket). There's also a company who makes/made a composite spacer if I remember correctly. Maybe someone will chime in with the name. People liked them because they don't transfer heat I guess.