Shod are you eibach 20/25 or 30mm all round. So many variations.
You see many variations but there are only two from Eibach, either Pro-Kit or Sportlines.
Pro-Kits (black painted) compared with a normal suspension are -30 mm, compared with a sport suspension (like GT/GT Sport have) are -15 mm and compared with the GTI suspension are -5 mm (hard to notice any lowering, you'll notice the better handling and ride comfort).
Sporlines (red painted) compared with a normal suspension are -50 mm, compared with a sport suspension (like GT/GT Sport have) are -35 mm and compared with the GTI suspension are -30 mm (the perfect lowering in my opinion, better handling and a bit of improved ride comfort).
H&R just has one version of springs for GTI that are -30 mm that are very similar to Sportlines. They are painted blue. Other Golfs versions have different models of H&R springs that are similar to Pro-Kit (painted black too) and to Sportlines (painted red too).
If you want comfort go for a less lowering version. If you want better handling on corners and better stance you can go for the Sportlines or for the H&R -30 mm.
