Originally Posted by Slidefox

A fellow mustang owner... (I own a '00 V6).... We can do the simple OBD2 hand held units.

The Z is definitely a little more tricky. Depending on the EMS you choose they have to be installed and tuned by a dealer. Most units will give you full control over fuel, timing, boost, etc. Some units are piggybacks that use the OEM ECU to control all the basic function, and the piggyback unit modifies the signal before it reaches the engine.