I have Belltech myself, i have not heard heard anything bad about them at all, the most important thing about how low your going to go is your wheel and tire package. You have to decide the overall stance you are going for. you don't want to lower it and then get some rims and not be happy.
I bought mine from stylinconcepts.com. I bought a DJM 2"/4" drop kit and replaced all shocks with Toxic Shocks. Very pleased with the look and ride. Install was easy EXCEPT for the hangers in the rear. Pain in the butt drilling out the rivets that held the stocks ones in place but other than that a good do-it-yourself project. GOOD LUCK!
i say go with beltech too. i would say a 3/5 drop looks a little better than a 4/6 or lower. but thats just me. whatever you do you'll be into new front coil springs, shocks, rear shocks, rear leaf spring drop shackles and hangers too.