Thanks for the feedback.
I was referring to actual hard bumpstops in the suspension. I have lowered cars before only to find 'bottoming' under compression,where the hard (or even progresssive) solid suspension bump stops start to significantly add to the effective spring rates. This give the skittish unsettled bounce over big undulations or bumps, dips (A sudden increase in spring rate under load)
I don't know where they sit (I havent looked on a Golf) in the shock itself or the suspension ?
On BMW's it's quite often an issue but less often understood !