Here'* a new concept that I'm learning about and going to do to the motor I'm rebuilding for school, notching the heads. You but a notch between the valves on each cylinder. It changes air and fuel flow I guess and makes it more efficient and increases power at the same time, or so the legend goes. That'* all pending results from the motor that I'm building though. Still kinda skeptical...have you guys heard of it? IF it works, I'm doing it to my L67 on top of all the other mods.....Not to get off subject or anything....They say there can be mpg gains of up to 30% doing this.