Supposedly they are the W5 numbers that he has posted on his site.
I can say this. A extremely respectable guy in our community flowed them and they didnt bust 300 at any point. Peaked at 297
All i can say is they made 708 horse on a dyno and backed those numbers up perfectly at the track. 140@ 3220. So i doubt a sub 300 cfm head could make over 700. That said, i aint a guru.... lol