Rat Bastid! I never drag raced it with the heating connected but did notice when I disconected the heating I had to increase the jet size, or more importantly with the water heating I could decrease the jet size!
Possibly because it needed more of the lighter fractions that vaporize at lower temps to make up for the fact that you were not vaporizing the heavier ones due to lower temps in the manifold.
Just a thought for those who may possibly want to understand the why's.......