Although its ability to provide 29,000 psi worth of rail pressure makes it extremely efficient, the factory Bosch CP4.2 found on the ’11-’14 6.7L Power Stroke flows roughly 20 percent less fuel than a comparable CP3. While this isn’t noticeable at stock power levels, the CP4.2 falls short when a longer injector on-time (i.e. pulse width) is commanded via aftermarket programming. Increased injector pulse width renders the pump unable to maintain adequate rail pressure to make sufficient power. Even with the factory turbo scrapped in favor of a freer flowing unit, the CP4.2 is only capable of supporting 500 to 525 hp. And with the stock piezoelectric injectors being capable of supporting 650 to 700 hp, you can see why so many enthusiasts install the H&S Motorsports dual pump system on their trucks.