None of the Duramax engines need a lift pump. But they all could use one because the CP3 and CP4 suck the fuel from the tank to the engine instead of pushing the fuel from the tank to the engine. They really are a good addition even to the LBZ. Thats why I put one on mine. Even at 225,000 miles. If a person wants extra filtration throw on an Air Dog or Fass system but go with the lowest flow you can. I think they are 95 - 100 gph. The only reason you would need more is if you wanted to boost your hp up over about 500.
I would never run a WIX fuel filter on a Duramax. They are a junk filter for that application. I highly recommend the AC Delco, Racor Fuel filters. I do run the WIX oil filters though.
Dont forget to change your tranny filter also. I only run Allison and always make sure the magnet is in place.
There is enough info over on the Duramax forum to keep you reading for days about Duramax engines, fuel filters, and lift pumps!