Diesel Pre Filter plus Factory Filter

[Plasnart]

The only reason I think, is if you live in a remote area where fuel supply is less than desirable.

^^^^^^^ what he said ^^^^^^^^

Really they are beneficial to catch water in fuel and other contamination found in crap tanks. Even the onboard tank.

Umm yeah, but the standard fuel filter has a water bowl and drain valve at the bottom, so why do you need another to complicate things?