Agree with Chunktone. If you want the Brad Gillis/Vai flutter thing, go with fewer springs. Less flutter, more springs. I kinda like the flutter, the guitar I have that does it the most is a Brad Gillis Fernandes I have with a non fine tuner old school floyd. I think it works well because it doesn't have the fine tuners hanging off the back - I can bang the guitar body like Brad does and the guitar does this freakout flutter thing. Not that you asked specifically about flutter, but another flutter helper is a tight trem arm as a loose one dampens the flutter considerably.