I have the Edelbrock panhard bar. Serious improvement over stock in handling, especially on the highway, my Tahoe doesn't get blown around in heavy winds anymore. I can do quick zig zags at 70mph and not feel like I am about to flip. And I installed this AFTER my Hotchkis sway bars, so this was in addition the already great handling. Gives the rear a very planted feel and really helps the sway of the rear half of the Tahoe around tighter turns.
I paid $75 shipped and would have happily paid $300 for the results I got with it. I added boxed trailing arms later, but didn't really notice a handling difference with them, I can do 4wd launches straight as an arrow but not sure what to attribute that to, steering or suspension or both.