Does anyone know what the VP44 requires in Gallons Per Hour fuel flow on a stock engine? Doing a search gives conflicting info with nothing available from Bosch.Filters are rated in flow amounts per hour, not the psi.Mike, you said 45 GPH is enough, forgive me for beginning to wonder about all this, but, even our stock filter on the engine may not be rated for enough flow. Look at the restrictive banjo fuel system. It wouldn't be the first time I could be wrong on something like this, But why isn't this information available on a Google search from Bosch?Some guys are saying we need to increase the size of the return line too.

Here is the low down... This is what I've read from Bosch (not Dodge or Cummins). "Bosch VP44 injection pump requires 70% of the fuel to be returned to the fuel tank for proper cooling and lubrication of the injection pump"Ok.. 70% of what?Here we go. Using my scanGauge II in my truck the highest GPH rate I've ever seen is 20 GPH at WOT stomp. So if the lift pump is 100 GPH (AirDog or FASS) then that's 20% being injected and 80% being returned. This math changes based on lift pump volume so if you have 150 GPH lift pump that's 13% injected and 87% returned.So I would aim for a filter setup that capable of handling maximum volume of your lift pump. Like I'm still running the stock filter and the 3 micron filter on the Airdog with only a 2 PSI drop in pressure. This is good this means there is very little restriction and the lift pump and plumbing are keeping up with the VP44 demands.On a true stock system with 6mm lines and stock Carter lift pump it really restricted. Stock Carter only puts out 35 GPH so that's 57% injected and 43% returned. Then the stock 6mm lines are only rated for a max flow of 75 GPH with 0 PSI at the far end. Also I know the older can style filter housing are restrictive to like 35-45 GPH if I remember right. That's why the drop in can where designed later to replace the restrictive version.