JEGS sells the Promaxx heads for the same coin as the RPMs. Sidewinders are considerably cheaper - starting at $850 including valves. Why are the Promaxx so much more than the Sidewinders if they are the same casting?
How much $$$ for the different porting stages for Sidewinder heads? Am I right assuming that all the porting was done by hand or is there already a CNC program? I'm in the market for new heads and the Sidewinders seem to be the answer.
