The DiMarzio YJM signature pickup is now called HS-4.
In the Alcatrazz days he used to use the FS-1 which is slightly hotter than the HS-series/YJM but its not humcancelling.
Then he played the HS-3´s for a long time, like 10-12 years or something. HS-3 in the bridge and neck, stock strat pickup lowered flush with the pickguard in the middle. Then in 1995 he got the YJM which he used in the neck and middle, and an HS-3 still in the bridge. The YJM is very, very close to an HS-3. Only difference according to DiMarzio is the vintage stagger which affects string balance which, in turn, gives you a slightly clearer tone on the unwound strings higher up the neck.
The thing to remember about these pickups is that they are very low output. Yngwie of course uses the DOD250/308 overdrive cranked into his Marshalls and that creates the distortion. He's quoted in an old Guitar Player issue saying that he believes that in order to get the best, clearest tone the signal from the guitar should be totally clean without a hint of distortion and then you overdrive it severely with an OD hitting the amp. It obviously worked as his tone, and playing, back then was out of this world. In the same interview he also stated that a single note shouldnt sound distorted, it should just sound sweet and sing, and when you hit a power chord, then you hear the crunch and distortion.
When he switched to the much hotter SD Furys IMO his tone went from a clear, bell-like tone to something over-compressed and way too distorted. Mud and mush.