Well I’m not one for making any mount other than solid but if a shim or spacer is in order for you, I can machine a pair of them with centering dowels and machine the bottom of your exiting mounts to accept the dowel pins. I’m not keen on just slipping a shim under a mount without some kind of locking pin/dowel arrangement as there’s too much chance for slippage and bolt shear without them. The mount-to-chassis bolts on the Gti are only 10x1.50mm in size and i imagine they’re the same for the 1.8’s and Tdi’s.
Not difficult at all to do, just need to know how high and need your mounts. I can get the billet.