I have 4 Bilstein sports in my Impala right now, the 1104/0929 combo. It improved the handling like night and day, but I don't like how it rides in the back. The whole car rides pretty hard, but mainly in the rear. The tires have small sidewalls, 235/60.
My car has NO sway bar, and it has those TRW Hef-T-Coil variable rate springs in it, which are also new, along with some poly spring isolators. I did not put these in- I was going to but didn't have time, and this shop down the street did it for me.
When I go over a decent sized bump, the car jounces back up and down kind of hard in the back and it just doesn't feel right. If these shocks are just supposed to ride this way it wouldn't bother me but I dunno...I also get a lot of noise in the back as well, mainly the right rear, if I take corners or drive up a sidewalk curbcut or something, I will almost always hear a big "BONGGG" noise from there. Both sides of the rear suspension give me a clacking sound too like somethings loose. It's getting annoying. I'm not certain, but there are new exhaust pipes in the back that were there before I got the car, and they seem like an amateur install. Looks like maybe one is too close to the spring and possibly hitting it when I go into driveways, around corners, etc.
Anyway, a few years ago I had the same rear springs and 4 KYB Gas A Justs put in my old green Impala at the same shop. I seem to remember it riding smoother and handling about the same, and I thought the rear end was a lot higher. I did have 255s on the back though.
I didn't know what you guy's opinions might be on each brand, if I should try swapping the shocks to see what happens, etc. I've heard that KYB is a good shock for it's price range but Bilstein is the ultimate...I installed them in my Blazer and that corners real nice too.