Warren was introduced to FZ just prior to the Halloween '76 run by Davey Moire, one of FZ's sound engineers and a friendship ensued. He performed the "Story of Ms X." at the '78 Palladium Halloween show as a guest, and was a full member by the resumption of the tour in February the next year. Warren provided guitar, organ, and/or vocals for Joe's Garage Acts I, II & III, Tinsel Town Rebellion, Shut Up 'n Play Yer Guitar set, You Can't Do That On Stage Anymore Vol. 1, You Can't Do That On Stage Anymore Vol. 4, You Can't Do That On Stage Anymore Vol. 6, Frank Zappa Plays The Music Of Frank Zappa and Trance-Fusion; also for the Beat The Boots disk Any Way The Wind Blows (BTB).
Referenced in Catholic Girls as a "catholic boy".