ok, im not a professional, but im a vai fan n i have some words for u...
focus on the equipment...

hes always prefer ibanez jem stuffs, so theyr all 24 fret n soundin like superstrat... so u can check out the specs o his guitars... u know, about pickups or tonewood etc...

i heard hes also like valvetronix things, that means he has tube n solid tone at the same time...

basically he use everything in limits... great tone range with screaming high ends...

these all i can say, please correct me if i twaddled... :o
(sorry for my english btw...)

ps: hes usin "morley bad horsie wah" :)