I just installed these:
It's the 12.88" Superlite 6R kit:
http://wilwood.com/BrakeKits/BrakeK...e=Buick&model=Regal+Grand+National&option=All
Haven't been able to beat on them very hard yet, but initial pedal feel and bite with Hawk HP+ pads is really good.
This 6 piston caliper is actually smaller in terms of piston area than the four piston Dynalite it replaced (you can see the old caliper hanging in the background). No noise yet, but these pads will probably scream at me once I've put a track day on them. One thing I did notice is the new calipers are considerably stiffer than the old one. The pad retention bolt also serves as a mid-caliper bridge brace and there's a lot more meat to the caliper than the old one. I could hear the old calipers flex when I stomped on the pedal.
Install was just about an hour per side, not including bleeding. But the machine work to the spindles had already been done.