Gunter,
Sorry for the confusion. You are correct that the Mile High Challenge and Racing the Rockies are Rotax and Spec Shifter.
As The Track at Centennial continues to build a well run, safe racing program that is stable, the Rotax motor has proven to be a great investment for the racer. I am committed to protecting that investment. We can help you find a motor package for your new interested parties.
Rod, If you are planning on racing at the Grand Nationals, you will need the current head. It is not required for either of the series run here. You can find all the rules at http://www.GoRotax.com.
If anyone has questions regarding Rotax or the Series run by The Track at Centennial, feel free to call or e-mail me directly, so you will get the straight answer.
Competitive and safe racing to all…
Jim