A lot of the kits come with Doetsch Nitro-drop shocks. They're O.K. I found them to be lacking when playing in the twisties.
Right now I have the Belltech Street Performers. These I like. More of a true performance shock. Some members here don't like 'em.
Others here have had success with using late '60's Impala shocks in the rear. Monroes? I have no experience with those.
There are others here that swear by Bilsteins. Again, I have no personal first hand experience.
My biggest whine about the lowering kits, is that they use a front spring that mimics the ride of a stocker, which is definitely not performance oriented. Too soft/bouncy.
When I get into another round of suspension work on my '98, the lowered kit springs are outa there! They'll be replaced with a set of stock V8 springs (not V6) that have been cut down.
Cutting the stock ones increases the spring rate & really helps to get rid of that soft bouncy 'commuter' ride. Buddy's truck that has almost the same set-up as mine, but with cut springs, handles like it's on rails! A firmer ride for sure, but his truck just feels so much more connected to the road. He doesn't bottom out his suspension like mine does in the same spots @ speed. He just kills me in the corners!