Essential Zappa: what's missing from my collectio

I'm more interested in the instrumental side of Frank / Mothers. This is what I have so far:

The Yellow Shark: Personally, I think this is far and away
the best thing he ever did.
Waka Jawaka
Apostrophe / Overnight sensation
Civilization Phase 3
Hot Rats
Essential Zappa
Classical Zappa
Orchestral Favorites
Studio Tan
Guitar
Freak Out

It turns out I had more than I thought. Looking to fill in the holes in my collection. I took out "Lather" from the local library and thought it was ok. What about Chunga's Revenge (SP?)and Mothers Live (think it was a live concert recording from Austin, Tx.)?