First, always replace the rubber grommets. The first time I replaced mine I didn't order enough so I reused two of them. Sure enough within a few months it was leaking from the old grommets.
Second, the VC bolts are designed so that they bottom out on the head after compressing the grommets slightly. Tightening beyond that will only stress the bolt and threads. So I was advised by my indy to use a small ratchet, 1/4 or 3/8 max, and tighten them down until you feel the bolt bottom out. Then tighten by feel beyond that just enough so that they don't loosen up.
I did this when I replaced the VCG the second time and have had no problem over a year later.
2003 E39 M5 Lemans Blue: The most amazing car ever built
1999 E46 328i Bone stock 5-speed: Soon to be track rat
235K and still running strong