LOW RES:
All figures at 28" of water. Data collected on Superflow flow bench. Intake Side.
As you can see, the Ultimate head adds over 50 CFM over and above the FR head. Pretty astounding.
Exhaust side. The Optimized (stock valve) head loses a bit on the bottom but makes it up on the top. This illustrates the need for the larger valve on that side, and the dramatic gains seen on the Ultimate head are certainly note worthy.