Your struts are 50 mm. Have a look on your front brake calipers. You'll notice a "FSIII" on them.
That's the proof for 50 mm struts.
I'd get a Bilstein B12 Pro suspension kit. The stock dampers are way too soft for Sportline springs.
If you really need to slam your car get the Bilstein B12 Sportline, but the Sportline springs are too
low to keep reasonable ride comfort.
Eibach make the springs for the kit, Bilstein makes the dampers. Nice kind of joint venture.
Also keep in mind there are Mk.V- and MkVI versions of both. For a good ride choose Mk.VI B12 Pro,
if you wanna go low get a Mk.V B12 Sportline.
Why? Mk.V Bilstein dampers are stiffer than Mk.VI Bilsteins. The stiffer Mk.V ones do handle the short
(= stiff) Sportline springs better, the softer Mk.VII Bilsteins offer an amazing good ride.