I posted unboxing and installation photos in the earlier
http://forums.pelicanparts.com/porsche-911-technical-forum/970881-sway-bar-upgrade-4.html#post9937690 thread.
I installed the Eibach kit on my 1983 SC Targa. The suspension is otherwise stock, although the front end has been lowered to around 140 mm (about 25 1/4" at the front fender arches) and she is running 7x17 F and 9x17 R rims with 215/45 and 245/40 tires.
With the Eibach bars, the car handles much flatter than before and understeer is noticeably reduced in spirited cornering on twisty rural public roads. Left to right and right to left transitions are snappier and the car feels much more "planted." Body roll feels nearly non-existent. The other most noticeable effect is decreased independence of the suspension when turning into a driveway or going over a speed bump at angle. I don't find it annoying, just different.
Although others have said that sway bars should be upgraded as a fine tuning adjustment
after stiffer torsion bars and better shocks, I have found that the Eibach kit works nicely with my stock suspension. Perhaps if I had stiffer T bars already installed, the effect of the sway bars would be less noticable. I still intend to upgrade the t bars and shocks, which will collectively cost more than twice as much as the Eibach sway bars and be a more time-consuming install. If I get as much incremental improvement out of those upgrades as I got out of the Eibach sway bars, I will still consider them well worthwhile.
The only negative I can find with the Eibach bars is that it would be difficult (on my car) to set the front bar at the softer setting, and if they were installed at the softer setting, I would be concerned about bending or breaking the end links at full droop of the front suspension because the middle of the links would be forced against the metal end loops on the control arms. IIRC, I posted about this in the earlier thread.
My bottom line: for a car with stock or near-stock suspension, the Eibach sway bar kit provides great bang for the buck. If you have a stock or near-stock 911 and are wondering if the kit would make worthwhile difference...you won't be disappointed.
I can't speak to how much difference the Eibach bars would make on a car already equipped with stiffer suspension. In the earlier thread, fellow Pelican Douglas Bray seemed quite pleased with the Eibach bars on his cab with significantly upgraded suspension.