The AMB system comes with a full set of instructions on mounting the transponders. A separate internal mount, that comes with most kits these days, works or drill a 1/4" hole in the middle of the body at the transition from the hood to the windshield on sedans. On the wedge type bodies it can be a little more difficult to find the proper location.
The important thing is to put the transponder in a location where it can not make contact with the ground, the track (right side up or inverted) and can not be hit by other cars. They are somewhat sensitive and in the order of $75 to replace a single (rechargeable) transponder. The non-rechargeable personal transponders are slightly less money but the location is just as important. Also make sure that there is no metal chasis or carbon fiber chasis components between the transponder and the timing loop.
Best thing (and I know guys are not prone to do this) READ THE INSTALLATION INSTRUCTIONS.