With so much discussion on this topic, let me point out an important point about the return-line issue :
While it's entirely possible that someone will find (or has found) a single pump that will deliver volume equivalent to the double-pump systems on the market, there will continue to be one pivotal difference between these systems. Without some provision for flow modulation, a single, huge-volume pump is just useless for a street car. The Quad Air (Red Armstrong) Double-Pumper system, for example, incorporates fuel volume from the second pump ONLY under boost.
While this may seem like an unnecessary complexity, it's not. The reason for this on-demand-only activation isn't just to extend the life of the pump, or to cut noise (although those are positive aspects of the system). The boost-switch activation of the secondary pump is so that the return-line is not overpowered under normal driving conditions, which would cause all kinds of unwanted side-effects...specifically, the potential for line-pressure to skyrocket. I've used two different generations of the Quad-Air Double-Pumper system, and for my cars, it's money well-spent.
On the other hand, if someone were to develop a single pump that meets the following market demands, I'll put one in my next car, and any sub-11 second machine I work on:
1. Is capable of the ~400 liter/hour numbers (at WOT pressure requirements)
2. Allows SAFE modulation of the pump output under normal driving conditions.
3. Provides a drop-in installation, like other competing systems.
4. Offers a significant cost savings, by at least 25%.
5. Has a product warranty rivaling or exceeding competing systems.
