Im with stevek666, runinruder and keranu, I've always assumed that it was like veegz. That doesn't make it right, but I don't think vay gus is necessarily right because we don't always pronounce things exactly the same in the US. Like how Ys is pronounced ee-su in Japan.
When going with made up words, the katakana pronunciation is generally an accurate guide to go by. If it was supposed to be pronounced veegz (assuming you mean a 'j' as in 'jam' sound for the g there) it would have probably been spelt BI-JI-ZU, or for a hard g, BI-GU-ZU / BI-GU-SU.
Ys is spelt I-SU in Japan, but not pronounced ee-su, as it is common practice to drop the U in SU at the end of a word.
i.e. DESU ('is')= pronounced DES. It can be pronounced with the U but usually.
I find katakana very handy to find direct pronunciation, excepting of course that original English words will be a little distorted. Mind you, on translation a lot of sounds are altered due to the American's habit for certain vowels. A good example is Pokemon, which should be POK-EH-MON, not POHKEYMON.
