When released in 1969, Hot Rats represented a major shift for Zappa. The solo effort found the guitarist/composer eschewing the Mothers' absurdist art-rock for jammy jazz-fusion. Except for the grimy "Willie The Pimp" (featuring Captain Beefheart's mush-mouth growl), every piece is instrumental. What's more, three of the album's six cuts break the eight-minute mark. The most potent is "The Gumbo Variations," spotlighting as it does the ensemble's mix of brutish groove exploration and dexterous interplay. Pay close to attention to Zappa's full bodied and slyly phantasmagoric production.