I've got a set of new ported Brodix B1-BA's with new Jesel shafts that I'll make you a killer deal on. Don't know why they had so many variants in this head as far as flow, but this set is 314 cfm @ .600 with awesome low lift numbers. Koffel's did the port , flow, and valve work. They designed them and seem to know how to make them work.