Thinking about a new intake manifold . What is the difference between the Edelbrock Performer R.P.M. and the Edelbrock R.P.M. Air gap , I realize the Air Gap has a space to keep thing's cooler from oil heat but will my Holley electric choke work o.k. without a heat riser passage. Should I go with the R.P.M. so my electric choke will work properly, or will the aluminum manifold conduct enough heat where the crossover won't matter anyway?