there are plenty of words we pronounce differently than the words they came from. that's why we call this english, not "a bunch of stolen words-ish." and since english is now the dominant language world-wide for global affairs, the one other languages have to steal FROM, i think it's safe to go with the english version, just like we would have used the german version or latin version hundreds of years ago.
therefore, it's vih-sta. you know, those things americans see when they look out of windows.