LOL, If I believed every thing I have read in the owners manual I would have thrown out my ASP Red heads long ago. The manual says to run them on 15% nitro. I think it would have to be 40 below zero for that engine to run on 15% nitro without having a meltdown from the detonation. Maybe a missprint, they must have accidently put a 1 in front of the 5.