Which tracks on Improvision are you speaking of? I was just listening to part of that album earlier, and all of his solos that I heard had no effects on them.
Didn't hear anything on track 9, but there's something at the very end of track 1, although it's subtle. Looks like he's using a DL4 in the vid of it: http://www.youtube.com/watch?v=UjQ3fpSp5sA
It may have just been someone in the studio recording it for himself. TBer Peter Parker may have actually been there for part of it- you may want to ask him.