Bilstein uses B8 dampers in the B12 kit combined with eibachs. But you could use B6 as well. B6 an B8 is exactly the same damper with exactly the same characteristics, just B8 has shorter piston rod and thats why it is used only for lowering above 30mm. B6 work from standard ride height up to 30mm lowering. In the past I contated Bilstein about this and they told me I can use both with -30mm springs. In the B12 kit they include B8.
I have the B8 on my Twin Spark. I used them with H&R springs in the past and now I have Eibachs so the B12 kit, I just bought the parts separately
Its definitely not too firm, neither my mother or girlfriend complain. On the other hand, my father complains, so its individual. Of course its sporty firm, but well damped. If you want to lower the car, go for it. However, to anybody that doesnt insist on lowering for looks I would recommend to go for B6 and keep the OEM springs and ride height. Probably best option for a daily driven alfa on bad roads.
This month I will be removing my B12 kit and putting original suspension on it. Twinspark is now used by my father as well and I have GTA as a toy. So for him I am swapping 17" wheels for 16" and puting back OEM suspension.
147GTA,Grigio Metallico,Imola leather,3.75l conversion,ported heads,F575 TB,Carbon plenum,Stainless manifolds,EQ pipes,Supersprint silenced cat back,18" GT multispokes,KW V3,Galfer 6pot 355mm,Brembo sport rear
147 1.6TS, Nerro,Beige Interior,Galfer Extreme Brake kit,2,0TS intake manifold,Custom ex. manifold,200CPI cat,Supersprint silenced center + OO backbox,GTA spoiler,GTA side skirts,GTA headlights,Blaupunkt LA MP74 + Focal + MacAudio + Dynamat + HERZ subwoofer