thanks for the clarification Karl.

but why not use one that is both linked to manifold pressure and is rising rate so that on boost you get a higher increase in the fuel rail pressure than in the manifold? i cannot see any disadvantages, only that it must be a cheap way to extract more power out of small injectors, or controlling a reasonable flow rate at idle and low rail pressure with large injectors.

going back to the "Gunship conversion", i have read that the boost pressure has a high midrange but tails off at the top. with a RR FPR, could you not maintain a higher boost all the way to the rev limiter on std yellows?

having said that, the boost at that level is off the scale of the MAP sensor, so why not go 3 bar MAP and greens route? the cost of the greens must be more than a RR FPR? but then 'off the shelf' chips are available for 3 bar and greens i suppose, whereas the yellows with RR FPR would need custom mapping.