Ultra light x-axis for custom 3D printer

I am always developing my printer, trying to make it better. The newest adittion to the design is a light x-axis. The extruder is removed from the moving x-axis and placed on the frame. The design is made for pneumatic fittings. I use a bowden geared extruder to feed the hot end: http://www.thingiverse.com/thing:60531 Only the hot end is now moving, making higher printing speeds possible. The quick fit design for the j-head is derived from: http://www.thingiverse.com/thing:30951