Yep. And this possibly where the experienced porters look to the NA head to work on from scratch give there is additional meat around the place to favourably reshape the port! With regards to the guide bosses, I did a set of heads for my racecar myself many years back. I took a tip from a mate, a very old mate actually who suggested instead of removing the bosses altogether which is almost universal, i actually blended and shaped the protruding bosses, along with the tips of the guides into a "teardrop" or wing section with a blunt leading edge tapering off to a relatively sharp trailing edge. I basically ignored the large roof radius and just shaped it to a consistent radius and spent my time reshaping the short radius to match consistently the longer radius and did a quick port match to the manifolds with a final tart up with a coarse mop. Kept volumes as close to stock as possible. Basically just a mild "port and polish" I had those heads given a 3 angle valve job and later flowed against a set of full house grubbed out highflow heads belonging to a prominent and successful local racer. The flowbench guys eyes widened up, along with mine when we got flow figures within 5% of those million dollar heads against the couple of hours I spent dicking around with some old heads i found in the rubbish!!!! The main point here is not to blow my own horn and swing my cock about my own results but to emphasize that when it comes to gasflow, less is often very much more and its often the combination of very subtle changes that give the bigger results. Another point almost universally ovelooked by the less informed crow is of gasflow behavior in a port when under pressure!! Things you tend to expect as normal when talking NA become rather insignificant under pressure!!!!!! E
