Hi Prodater,
I recall doing a series of encodes at different VBV values, from 15 to 60, and the optimal (center) value was ~48. Below 35 and above 55, stuttering started to appear on standalone. This were 352x240 KVCDs.
The VBV value will have to be different, depending on the resolution used, because the higher the resolution, the more bits you have to deal with. So normally the higher the resolution, the higher the VBV value, of course, up to a point.
However

if you look at an MPEG-2 MP@HL at 1920 x 1080 video, you will notice that the value is indeed 488, so I assume that for now, that is the maximum value
-kwag