Head Porting, is something very few people can do and make a big improvement.
Today's manufacturers spend tons of time and money on head design to improve flow, and still stay within the boundries of making a stock engine perform better than their competition. Which at this stage in the game, it's hard to tell the difference between one or the other. The heads are so good today that you really have to know how to improve what already works well. But you have to know where to start and where to finish. If you start out wrong, you will finish the same way, and even a good flow bench and 40 hrs later you might redeem yourself to the point of not having to buy the customer a new head and sending it to someone who should have had it to start with. Then there is epoxy! There has been times that I have used epoxy on my heads, For instance on some supercross engines, where the course consists of tight corners and close jumps, and no long straight aways. Where torque is a factor and top end is not. And on some of the old heads back in the days before the down draft style. Also some heads just have bad casting, and become porous, making it easy to create a leak inside the port . It happens sometimes, and a little apoxy done right will never create a problem. Bottom line is, there is a lot of different port designs for different Horsepower needs, and that is where experience in reshaping ports and valve angles, in configuration with the right camshaft and exhaust results in a winning combination.
After thirty (30) years and hundreds of heads I consider myself a master at porting.
( 4 stroke heads and 2 stroke cylinders )
If you already have an engine builder, you need to try my head.