I just got this from HAAS's website as it pertains to the GT10:
Would this mean that you could actually get 4,000 RPM?
Just something to look at.
5C Pneumatic Chucking System, 1.06" (27 mm) drawtube thru hole, 4000 rpm; includes 5C collet chuck, rotating cylinder and drawtube AC5C-KIT
5.3" (135 mm) Pneumatic Chucking System, 1.18" (30 mm) drawtube thru hole, 4000 rpm; includes chuck, rotating cylinder and drawtube ACH5-KIT