I don't think (I could be wrong) that the supermag was ever made in a Wingmaster configuration. The Supermag (3 1/2") has always been a crude express model. I have a supermag from 98 or 99 I think with out of the box extreme roughness. I polished the dickens out of it, and now it's almost as smooth as any wingmaster.
I much recommend the Supernova or Nova over the Supermag in any case.