I have had all three heads, Stage V on a pump gas blown hemi, CNC ported 440-1 on a pump gas motor and I do have a set of B1 not used yet. The B1 flow 430 cfm at .700, .800 and above, the 440-1 flow 370 at .700 and the ported Stage V flowed a tiny bit better than the B1s did If I was making the choice you have I would go with the Stage V based on the parts and intended usage nothing like the WOW factor of a Hemiroid