I thought the essence of a CNC port was really so you could essentially purchase a slightly more economically priced mass produced ported head based on an intricately digitally mapped and 'science out' hand ported (and flowed) model. To think the CNC would be 'better' than the hand ported model it was based on would be a stretch, I thought cnc was just applying modern mass production technology to a hand science as a means of keeping the unit cost and lead times down. I would think hand finishing a CNC set would be beneficial in terms of ultimate bench flow numbers but we're probably talking only 10ths of a percent impovements overall in practical terms. Ybut by hand porting above CNC you maybe pushing the safe limit envelope if the heads are nearly maxed to begin with.