I ahve this kit and I love it. It is VERY stout. The install can be a bit of a pain, only because you do have to do a lot of drilling. Once the holes are drilled though, it is a very strong setup. It drives, steers and flexes as good as anything I have experienced.
As for the sliders. They will work just fine unless you also use T&T's unibody stiffener kit. The kit adds 3/16" steel along the inner "frame" rails. I just welded 3'16's along the pinch seam portion of the sliders and they work great. If yours don't have the pinch seam, then you will have nothing to worry about.
One post said their customer service sucks but I have had great luck with them. I called them over and over again regarding different products adn they were always willing to help me and give me useful info. The kid there is a regular guy and he doesn't give you the professional, "Yes sir, no sir," but he'll tell you right and may include a couple of explicatives, but it's only because he's excited about their products.
I highly recommend them to anyone (and no I don't know them or get a kickback).
Good Luck!