Re: DiMarzios or Duncans in an RG321?
If it were me I'd be getting a Screamin' Demon bridge, Air Norton neck. Both work extremely well under high gain, both are outstanding for good riffs, both are harmonically rich, both are warm yet fiesty, both are amazingly responsive to your playing which could also result to huge picking attack, both sound amazing clean
Sounds like the perfect combo for clarity, except for output, but any reasonably high gain amp could fix that