spyder mod is were you mod an electro spyder frame to work with a mag. it is the cheapest way to get it to walk without badly short stroking with a mech frame. it won't be too fast, but its cheap.
here are the instructions-
http://www.automags.org/forums/showt...ight=spydermag
ofcourse i would just get an RT valve, and be done with it... lol