Why Steve likes 9th over Root:

GP: Your melodies tend to emphasize the 9th rather than the root.

Steve Vai: Yeah, that's just my taste - I love the 9th. That and the #11 are my favorite notes, but the 11th doesn't work as often. But I love the sound of Dorian with a major 6th that almost implies minor, and the same thing goes for the 9th. Where Yngwie might go to the minor 6th or minor 9th, I'd go to the major. I like Dorian better than straight minor, and I like cadencing my melodies on the 9th.

Steve's Favorite Mode(in 1990, anyway...)

GP: Lydian mode for Days!

Steve Vai: It's my favorite mode - I'm a sucker for it.
 

Stevie "Ramone" Vai on "Greasy Kid Stuff":

Steve Vai: The song was written in 1978 when punk music was the thing, It's Steve Vai's idea of punk: upper-structure triads and quintuplet melodies in 5/4. (laughs)
 

Twist and Shout over a pedal tone on the "The God Eaters":

Steve Vai: I'm a real sucker for creating a modulating tonal ambiance over a pedal tone, which is why I've got this D pedal through the whole thing. When you listen to it without the D pedal, the chords don't sound nearly as lush. I knew I wanted it to be dense. A lot of these clusters (multi tracked chords in "The God Eaters") set up a tonality you can't get any other way. I was going for an eerie sound. Whenever something sounded too straight-ahead, I tried to twist it. Then again, you can put a straight ahead chord between two other chords and give it a completely different aura. Sometimes you need a resolution to sound like you're speaking in sentences.

Steve's composition method:

Steve Vai: I have to be perfectly honest. I don't just sit and improvise stuff. I have to work really hard. Sometimes things come out (just that) easily. But those moments are few. I'm not so gifted that I can just pick up the guitar and everything comes out great. I have to work and pick and choose and knit, and on this record (Alien Love Secrets) I paid a lot of attention to my ears. A lot of those little things that I really like doing are just moments of cool articulation, just little moments of phrasing that probably go over everybody's head. But I work on them until they make me feel a certain way.

Jump into the Water, and Swim!:

Steve Vai's introduction "A Bit About Flex-Able" from the transcription book "Steve Vai."

Steve Vai: (Upon building his first home-studio) My production and engineering skills were minimal, but the only way to learn was to jump into it. I loved recording - anything. I must have recorded hundreds of hours of stuff. Anyone who was interested could come by and record.

The 10 hr Workout:

Steve presented the exact details of the groundwork that led to his current technique bare in a lesson with Guitar World.
The lesson has remarkable common sense, and is thus indispensable in learning and in teaching.
It covers picking exercises, chord studies, scale/mode studies and ways of thinking about your playing.
It is collected into a book, with other great lessons in "GUITAR WORLD PRESENTS PRIVATE LESSONS." Publisher is Hal Leonard (http://www.halleonard.com/) and I think that it is in print and readily available. Everyone should own a copy, seriously.