Systems return most of the fuel, that high GPH is intended to keep race pumps supplied under wot. It also helps to keep the IP cooled with fuel from the tank. The smaller 65 or so GPH pump would be fine for a stockish 4b

 

There's nothing wrong with the aftermarket feed pump except they are generally a bit pricey. If you use one just be sure it's the right one for your injection pump. If you have a VE pump then you'd want one for a 1st gen Dodge Cummins. Since you're using a brand new engine, it has a lift pump. If you went to one of the outboard models you'd probably want to remove that one and put a block off plate in the hole.

 

I was hoping someone had used a fuel air separator and had a positive story about quieter engine, more power, or something.

 

I've always ran the Fass 150 on my trucks & have one on my 4bt also! More options in the bigger filters for a Fass system also! I can PM you my buddy's site if you need a place?

 

there is a less expensive option... the raptor direct replacement. There is not really an increase in HP or mpg with the air/water separation. It could help injectors last longer with out as much cavitation. The filtration and fuel supply is likely the best benefit.

 

Well I have been running an airdog II 165 on my duramax for a year and more than happy with it.

You don't generally get a quieter engine with a lift pump/filter setup, but it does help with service life on the injector pump and injectors as your supplying fuel pressure to the injector pump.

Also helps with get up and go as there is instant pressure available to the pump.

 

Maybe its not on here, but longbow don made a homemade airdog for his 4bd1t.
Matt