the cai, assuming that it's of decent quality and size, should give a noticable difference, although not that much. it'll also give your car a more noticable growl up-top in the rpms.
as for the resistor...from what other people here just said, i wouldn't install it. also....an ecu upgrade doesn't do anything unless the car is fairly heavily modified. the stock ecu is the ideal engine computer for stock or near stock configuration.
what trim level is it?? dx, lx, ex?