Whereabouts are u in herts? I'm in Hitchin, if you like you could have a ride (as a passenger!) in my GT, it's got Eibachs and FSD's but 18" wheels, you've probably got 17". I don't think it'll take you too long to realise that what Dave says about FSD's not working with lowered springs is true, this is only my opinion as KonI reckon they work fine. My car handles corners amazingly but there are many times where I wonder if I've any damping whatsoever.
My plan at some point is to put The FSD's on my standard sussy sportwagon and probably Bilstein on my GT, might look into Koni sport though.
Dave , are u saying B8 are firmer than a koni at softest setting then you can make them more firm than B8? I'd be fairly gutted if I changed dampers and they came out harder than present.