TheFox,
a couple of points:
Suspension is the most important part of any car. It is the only part of the car that you use every minute that you drive, unlike power upgrades for example which you probably use for no more than a few minutes per drive, if that. The point I am trying to make is that if you get the suspension wrong, you will regret it on a daily basis.
If you look at the mathematics of suspension design (it's pretty much common sense too), it is apparent that the spring constant and the damping constant need to be matched (i.e. strong springs need heavy damping). You should therefore be rather wary of changing one without the other, unless the original setup is mismatched, which Saab's isn't (the standard units are, I believe, high pressure Sachs, and last for intergalactic mileages. I still have mine, if anyone is in dire need).
Adjustable dampers: as far as I know, most adjustable dampers available for cars are adjustable in bump (compression) damping only, the rebound (extension) damping is set in the design. This is unlike motorcycles, which, being much more sensitive (and having dire consequences), are often provided with both adjustable bump and rebound damping. The important point here is that Bilstein (as an example) tend to make stiffer springs and dampers than Koni/Sachs etc. Whilst you might argue that the soft end of the adjustment scale on a Bilstein is within the adjustment scale of a Koni, this is only the bump damping. The rebound damping will ALWAYS be greater, and you'll have to live with it.
The standard Saab suspension, in my opinion, suffers from too much body roll, and strange squidginess due to the soft wishbone bushes (as discussed ad nauseam in these pages). In order to reduce body roll, the primary change is to increase the spring constant (stiffness). If you shorten the springs as well, you will lower the centre of mass, which will help further. Then you need to change the damping to match the springs. One without the other is no good.
Manufacturers differences: well once again, in my opinion, manufacturers designs are biased to their home markets. Germany tends to have smooth roads with constant radius bends, Bilstein designs accordingly, i.e. strong springs and correspondingly "stiff" dampers. In the UK, this leads to a bone jarring ride, loss of tooth fillings/false teeth etc etc. Bilstein's suspensions have been known to lead to cracked VW Golf windscreens as the body flexes due to the stiffness and limited travel of the suspension.
Economics: changing the dampers is quite a bit of work. If you get front strut inserts, you need to accurately cut the tops off the existing struts. At the rear the damper/anti roll bar lower bolt may well be seized. So if you are going to do or pay for this work, not changing the springs at the same time is a bit short sighted, as well as the compromising the suspension performance.
Choosing a supplier: as mentioned above, the overiding aim here is not necessarily to get absolutely the best choice, but being certain that what you get is a big improvement, rather than a mistake. I chose Abbott springs with Koni dampers because I was pretty sure that it would be a big improvement. The fact that Abbott have their own springs made further suggested that they should be better than springs available from the usual sources. That I was paying someone else to do the work (rare for me, caused by pressure in the day job) was further reason why a mistake had to be avoided. As the rear dampers can only be adjusted off the car, Abbott's recommendation of damper settings was also valuable, as subsequent changes would cost time or money. I also got their anti roll bar bushes.
My experience so far: body roll is much reduced, steering response much improved. I would not want to go much lower as I occassionally catch the front as it is, and there is not that much clearance above the wheels (Note: you can't use snow chains anymore!!!) I would not want to go much stiffer as it's my every day car - I have other things for track day fun. All in all, a pretty good compromise with no real weak points.
This is not supposed to sound like an Abbott advert (you could easily find Konis elsewhere!!), and other combinations might be just as good for other people, but if you follow what some people have done successfully, you won't go far wrong.
P.S. Make sure you check the tracking at installation, and after a couple of thousand miles when everything has settled down. I forgot the latter, and my tyres are unhappy.
