GLENDALE, CA— Rock guitarist Steve Vai wowed a group of neighborhood children with his spectacular guitar pyrotechnics Monday. "His behind-the-head guitar solo was so wicked," said Jimmy Hetzel, 11, one of six children blown away by Vai's fretboard wizardry. "He also did this thing where he held the guitar between his legs and played it with a bow." The impromptu performance is believed to be the most impressive display of its kind since September 2000, when Joe Satriani "showed off a few licks" at a Southfield, MI, bar mitzvah.