Looking at the WRX heads I have sitting next to me it certainly is possible to do, but just a slight bit of research showed little to no change, negative torque numbers, or comparisons being made under different conditions, i.e. the only change was the grooves and "light port job".
Squish and flamefront action has been studied to death for almost 100 years in the relatively modern combustion engine. I know improvements could be made to most factory heads, but it would seem that manufacturers taking an extra 30 seconds to change the cast of the head to include these miracle notches with the promises made by the "inventor" would be a foregone conclusion, yet, they don't. If there was a true petrol powered vehicle on the road that from the factory came with these grooves and was considerably more efficient in the MPG department, i'd look further into it.
I am always leary of any miracle which is touted as "Patented" since you can patent just about anything, working or not. And from testimonials at Turbobrick and various other auto forums, the most notable improvement with the grooves cut was "Improved idle" and "Different sound". I'm not sold on the idea and even with my heads off my car and about ready to go back on, would not be willing to try it.