Stock Fuel Pump is usually maxing out at 300-350HP, those gains I belive you will still need the Kenny Bell Boost A Pump. Think over 250HP to 350HP will require the boost-a-pump. Over 350 the systems get converted over to return fuel system (seams like Mustang Fuel system / pump is what is used).
2001 ZX3 2.0L Zetec-
Hatch Nation #42
Going through Rebuild See "The TICK Build Thread" for details (http://www.focusfanatics.com/forum/showthread.php?t=289168&referrerid=62897)