They are talking about 25 heads. Now I have been told that if you have good flow you can compress but if you dont have good flow then you can not.
You guys who are using the 10 & 11 Heads I would imagine your motor flows preety well. Now are you guys changing the valve angles and making them flow or porting a certain way? It almost seems you guys are "shaving" the "eybrows" for more flow to me....