I run an AirDog 150.. I see no gains in fuel economy (significant enough to suggest it improved anything), nor in performance (unless I want to comment that throttle response is slightly improved).. what I DO see is hella better filtration and more positive water separation.. That makes it worth it, to me, in spades..
install: I actually did a partial write up on this.. There are a couple things I feel strongly about that differ from the instructions..
#1- There is zero cause, in my opinion, to tap the tank with an additional port for the AD provided supply line.. The inside diameter of the OE pick up and the AD pick up are near identical- given, the AD doesn't have bends in it other than at the top... to further complicate things, there is very little place to tap the tank and reach the bottom basin WITHOUT obstructing the float mechanism- which may be what leads to folks running out of fuel w/ 1/8th of a tank still showing- it's my guess that the float is actually resting on the pick up tube in those circumstances, and not giving accurate fuel levels.. the other likely reason folks 'run out of fuel' is that they tapped the tank in a place where it can't reach the lower 1/8th level...
caveat: If I had it to do again, I would have installed a sump, and draw fuel from the lowest point of the tank instead of through the top.. that is a certain way to get every drop of fuel out of it, but it's also a good way to introduce any debris from the tank to the pump, too.. That's a risk I'd be willing to take, though.
#2- You DO NOT have to drop the tank.. I DID drop it, but I found I didn't have to do so afterward.. If you lay under the truck with your feet toward the front, and axle above your torso, you can reach up to the basket.. it's not near as tight as trying to reach it from the wheel well.. I took a picture with my phone, got a good look at what was happening up there, identified the feed and the return disconnects, and went on feel alone from that point on.. I know this comment is going to cause some disagreement, but at least in my case, it was absolutely possible.. My arms are longish, but they ain't small by no means. I cold reach it easily from the passenger side.
It took me about six hours to install the AD.. this is mostly because it was my first time really under the truck (other than just dropping the exhaust, which took abotu ten minutes).. i went very methodically and my curiosity kept me poking around in matters that had nothing to do with the AD install at all.. I feel confident the job can be done in less than three hours- and most of that is prep and clean up.. it can be a messy job.. but seriously, after mounting the thing on the frame rail, pulling the quick disconnects and connecting the AD, running, soldering, and heat shrinking the leads, then what I explained above about connecting to the tank- it was an easy job that could be done easily in three hours if not 2/3rd's that time.
it is well worth it in protecting the fuel systems alone.. I hope you see economy and performance benefits, but even if you don't- know that it is a VERY good mod anyway..
oh- and more on point: I researched the crap out of it.. both FASS and AD have detractors and those that sing their praise.. either, or, and you'll be better than you are... I chose the AD150 because 150gmh is all I'll ever need.. the 165 will give you ample room to grow, and the ability to govern fuel is certainly a nice feature to have.