[quote author=JezMaz link=topic=74610.msg1354577#msg1354577 date=1177158219]
Search harder - there's a bunch of threads on this already.
FSDs are about street handling, not track handling. That's the primary difference between FSDs and Yellows.
Neither are to 'stop fender rub' - you've dropped it too low and/or running too wide a tire/wrong offset if you have rubbing issues. Shocks will not fix that.
The summary of FSDs is this: the car, even when lowered, rides flatter through corners and sits higher in its travel than with ordinary dampers.
Ride comfort is similar to stock (well, at least stock in Australia) but with far greater control.
They are excellent products, with no need to 'tune' them, as the internals basically take care of everything - normal dampers cannot do that.
Well worth it.
I just had FSDs installed (with the original factory springs). I must say that the ride has improved significantly. The little bumps and dips that used to upset the car is now much more controlled and in fact the suspension feels softer than before and much more quiet. But when driving more aggressively, the car seems to stiffen up to maintain balance. But the the transition (from soft to stiff) is very transparent. I am very happy with the switchover to these Konis. I had originally planned on getting Bilstein HDs because they seemed to last forever (in my last vehicle), but unfortunately, Bilstein do not make a rear unit for the Mazda 3, and I did not want to modify a Volvo S40 rear unit.
By the way, what do FSD converts do with their swapped out factory shocks? Mine have only 8000 km on them. Is there any demand for these suckers?