why would you use a throttle body spacer? on old gm vehicles that used a tbi (throttle body injection) a spacer increased the distance the fuel had to travel to get to the combustion chamber which gave it more time to atomize. the charger uses a direct injection (a injector for each cylinder) and a throttle body on the front with a butterfly valve that opens and closes to let air into the manifold. on this engine you can put on a larger diameter throttle body and higher volume injectors but this might require recalibration of the computer or a chip.
If you don't want a chip or exhaust why not try a short ram or cold air intake system.
