u/OG-Professor-Chaos

It started life as a brodozer now I'm turning it into my overlanding rig. I'm going to lower it down quite a bit now that I've decided the tire size I'm going to run and start out fitting it. When I got it, it had 24s and 37s, I sold them and bought these method wheels and a second hand set of 37 bfgs. Due to my remarkable ability to pick up every nail on the roadway in the county I was kind of forced into buying a new set of tires, when these 38x13.50 r17 Milestar Patagonia mt02s because they were in my price range and available. Somehow they're 3 in bigger than the 37-in bfgs. Now it needs to be re-geared I need to get my front & rear lockers put in get it lowered probably 3 to 4 in and start out fitting the bed.

I have a 2004 6.0 powerstroke with 190/30 injectors a stock turbo (for now) and an airdog 4G lift pump, the lift pump is having issues that I believe are in due to a failed o-ring internally. I intend to try and fix it but if I'm unable to or it has a different failure I'm going to go ahead and replace it.

What would you guys recommend between airdog ll 5G and a FASS lift pump kit?

My brother is recommending I put the FASS lift pump on it because when I eventually put a turbo on it I'll need it to support the power, I haven't done a ton of research but I know their kit supports something like 700 horsepower (more than I'll ever make).

When looking at the airdog 2 5G on their website it doesn't show a power limit for the unit so I'm not sure about that.

My truck will eventually get either an s475 compounded with the vgt or a jetfire stage 2 and I really don't want to have to buy another lift pump because I made the wrong choice. When it comes down to it there's only a couple hundred dollar difference between the two pump kits I'm just curious what the opinion is.

Update: this is going to sound dumb but I did not know the fpr in the airdog unit was adjustable.

I run a regulated return with an fpr on my firewall and it was set to 75 PSI while the pump was set to 60 so it was acting as a dead-headed system which explains the severe pressure drop (20-30psi) under load. I did check the o-rings because I was already working on it, I cranked up the regulator on the pump to let my firewall regulator handle the pressure and it's running perfect. Did a couple wide open throttle pulls and made sure the converter locked so that it had max load on it and I'm seeing a 3-4 PSI dip.

The only thing I'll say in my defense is that I didn't buy the airdog it just happened to be on a parts truck we bought for a body when we rebuilt my truck after a t-bone so I knew nothing about it. For most of my truck's life it used an in tank fuel pump using the regulated return to get a little extra pressure.

My '03 f250 with 8-in and 38s