What is the difference between these heads? On their website they have the exact same specs. Same intake and exhaust port volume, same valve sizes, same valve spring max lift, even the flow numbers are the same.
So if the port size and heads flow the same how can the say the E-Street is for Idle-5500 rpm and the Performer RPM from 1500-6500 rpm?
So where did they cut corners to save the $422 for the E-Street over the Performer RPM?
