Has Anyone Installed Torklift Stable Loads for rear spring assist?

Hey guys, I've been playing around with the new truck and noticed a bit of sag when I add the weight of my Outlander 850xt 4 wheeler in the bed (about 650lbs), then hook my camper up (tongue weight of 700lbs). I'm well within my load limits according to the Toyota manufacturer specs, but it looks like about 10"- 12" of sag at the rear bumper when loaded compared to when empty. I was interested in adding an airbag assist system when a buddy told me about the Torklift Stable Loads. One drawback, I have been told, is how 4 holes need to be drilled in the 2 overload springs on Tundras (I guess Ford, GM and Dodge use springs with holes pre-drilled in them) and a drill bit is included in the kit for Tundras. Has anyone done this? Is it worth the labor of drilling the holes? What I mean is, does it make a good difference so I'm not drilling holes in the overloads just to switch to a better system later that I should know about now? What do you guys know of from experience? This is my first Tundra...I've been a Chevy boy for a long time.