I've now had FSD's fitted to my NP car, without revised springs, for some 400 (mostly country) miles. I'm very pleased with the improvement in the ride and handling which, as others have found, becomes more apparent as you do more miles. I might fit the SS springs later, but I'm perfectly happy with the set-up as it is for now.  
However, I'm becoming concerned about the number of reports on the forum of various rumbling/knocking noises which appear to be coming from the FSD's on the rear, and wonder if there should be some kind of survey amongst members who've gone over to FSD's to establish just how many have had problems, as if it turns out that it's a significant number, perhaps we should make some sort of united Club approach to Koni.
I've recently sold my OEM's to a fellow Abarthisti so that he can eliminate or otherwise his FSD's as the source of his irritation.
I'm therefore crossing my fingers re. my own car.  

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