I'm very happy with it on my wife's tahoe. One major area of concern....don't let the rear axle droop too much when putting on the springs and put tension on the rear ABS lines. I did this by mistake during install and now have to buy new ABS lines since the Traction Control and ABS kicks in on occasion in parking lots. No biggie, just a mistake on my part.
But, I wouldn't call the rear too much firmer, just a bit "bouncier" with the LTZ suspension. Almost a caddy like bounce after big bumps. Not bad at all though, and the wife who is a pain when it comes to aftermarket stuff, really likes the kit. Ours is pretty dead on even, and you can even play with the rear height a bit if you have an LTZ. Someguys bend the ride height adjustment links in the rear to go higher/lower.