No. Stock rear glass must be retained. Only glass that can legally be removed is driver's side door glass IF and only IF your roll cage door bars protrude into the door cavity.
What some people have done (and this appears to be legal) is to mount a NACA duct to a flat plate that slides into the passenger door between the glass and the door and run a duct from there to your helmet.
I've also seen people just stick a duct out the window ty-wrapped/duct taped/safety wired to the mirror.
BTW, this isn't just an IT rule. Even in Production class where you are allowed to replace the glass with lexan, you aren't permitted to create any new openings in the window.
[This message has been edited by Greg Gauper (edited October 20, 2003).]
