TBI has the fuel injectors over the top of the throttle body, and MPI has one injector at the intake runner of each individual cylinder. There are a few things you can do to get a little more out of the squirrels, like exhaust upgrades, throttle body upgrades, and even gearing, but don't expect miracles. The 4 cylinder will put out more horsepower than the old 4.2 six cylinder, but where it is lacking is in the torque department. Torque is not as easy to make as horsepower. Hope you enjoy your new Jeep. Take care...Mike <img src="/forums/images/graemlins/oink.gif" alt="" />