Zappa was so musical that even his stuff that has vocals could arguably be considered in this list. That said, I would recommend some that have not yet been mentioned: On Sheik Yerbouti, Wild Love and Yo Mama are some phenomenal instrumental pieces with Terry Bozzio on drums and the Brecker Brothers on horns. Same with Zappa Live in NY, check out Purple Lagoon, same band as Sheik. I didn't see Sleep Dirt mentioned. This was another Terry Bozzio era album that has some rare acoustic guitar playing by Frank. Simply awesome. I tried listening to that LP the other night and just couldn't get through it because of all the pops. I just wore that album out. Gotta replace it. And to finish it off, Cruising with Ruben and the Jets, We're Only In It For The Money, Absolutely Free. I just ordered Trans-Fusion and I see the family just released Philly '76 (more Bozzio). As you can see I am a former drummer so I would say anything with Terry Bozzio, Ralph Humphrey, Chester Thompson, Ansley Dunbar and of course the greatest - Vinnie Colaiuta and you can't go wrong. Sorry for rambling and going off topic but .......