I run airlift 1000 series bags in my 2006 Denali xl. I love them. I have the factory Z55 air suspension and use them in tandem with the factory setup. Keep them maxed out at 35 psi whenever I tow, which has never been more than about 4500lbs so far. The 4300lb sea ray speed boat I pull for our family friends doesn’t make my rig sag at all. Pretty close to level and is very stable. When I pulled an 18 foot travel trailer w few weeks ago for a weekend camping trip my dear end was a tad bit lower than I prefer but still pretty close to level. And that trailer only had to go 15 miles from where we picked it up from its owner to the state beach we were camping at so it wasn’t a big deal.
When not towing and I have my detailing gear in the back I keep bags about 20 psi and it rides really well. As long as I have Yukon XLs I will always have the set up with bags. Next rig will definitely get an onboard compressor setup though with a switch in the cab and a gauge setup to monitor psi. So much easier than hopping out and grabbing the little compressor out fo the tailgate and manually filling them up. Lol.
