CNC head porting is over rated - the shops that bought these machines have to pay for them some how and they do cut way down on shop labor costs, as hand porting is very labor intensive. I am by no means a pro when it come to head porting, but a few years back I ported a set of 915 casting small block heads. I was fortunate enough to have a brother that ran the flow room for Navistar at the time so I had unlimited access to a flow bench. We flowed the intakes in their stock configuration and found a max flow variation of 3.6%. I was able to improve this to 1.6% by doing some methodical hand porting. I'm sure that someone who does this for a living could blow those numbers away. IMO, a professional hand ported head will outflow a CNC machine ported head every time.