Not to throw my hat into the "whose playing guitar" discussion... but to my ears it's Buckethead in the outro of the General, Slash throughout Monsters, and Fortus at the tail end of Monsters.
The General outro is pretty consistent with Bucket's wah sound/tone, fast picking, and half bends he does. I'm surprised so many people are 100% convinced it's Slash (which it very well could be)