(From Dragon's Fire, Volume 4, No. 2, March 1995) Yngwie says: "I use a hybrid set of Ernie Ball strings. The gauges on my standard Strats right now go 9, 12, 15, 24, 34, and 48. But this can vary somewhat, depending on which Strat I'm using (how deep the scallops are). On my Gibson, I use 9, 14, 16, 26, 36, and 48. I have all my Strats refretted with Dunlop 6000 frets. That's a big fret, but it works well with the scalloped neck and string height. Above the fret for the 12th position (high E) is about 4.5mm to 5mm. From the actual wood to the string is about 6 or 7 mm--it's really high, but I've become accustomed to it that way. I used to have it a lot lower, but I kept gradually moving it up because it sustains more."
Et voila le travail!