My point was that higher CFM isn't a reliable indicator of superior boosted flow. The infamous 2JZ-GTE Supra factory twin turbo head needs no mods, not even a valve job, to produce 700 hp from 183" on high boost. The extremely similar (by flow and mean cross-sectional area) RB26, 7M, etc. are down by hundreds of hp under the same conditions.
Why is the GTE head so superior? Toyota doesn't know, the port locations were compromised to allow larger water jackets (the N/A GE head has better ports, but only NA). It was an accident.
This is sort of the point I was questioning. With a boosted engine, it may be of importance to remove heat from the valves with wider seat margins on the valve job, and run valve seats that conduct heat better than to chase a few extra CFM with a narrow seat margin valve job, and inexpensive iron valve seats in the heads?
