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I posted this because I have been saying for awhile that I distrusted the approach many were taking relying so heavily on flow bench numbers and looking for great curves and shiny numbers especially from .500 - .600 lift. These heads did have special seat and valve work and minor deburing under the seats and high tulip valves, 1.900 Intake and 1.575 Exhaust. They are not heavy breathers especially at .500-.600 lift (take a look at where the piston is at between .500 and .600 in both intake and exhaust cycles) but they do have some very impressive .300 and .400 numbers. A little differant approach to porting and giving the motor what it needs where it needs it based on the CI and the cam. BTW this dyno is on an 8 year old 250 and the numbers are SAE and Winpep software is version 7, for the sake of honest disclosure. This is a new paradigm as we typically were used to 10.5/1 high lift cam 95" motors reaching these levels. The Thunderheader will make good torque but not low and at the top is probably costing a few HP IMO. FatCat would be even stronger.
BVBOB this is a baby cam with specs close to stock and only 18° overlap.
Regarding CNC
The machine removes metal by program 1st, hand blending afterwards. If there is core shift concievably places in the port could never be touched and others would have a very heavy cut. The HD heads late model can have up to a + or - tolerance of .040. The guys like R&R have all this dialed in when they use their own ports developed by Reggie.
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