spend money on everything EXCEPT the motor. its not worth spending a cent on, trust me. get wheels, lower it, get a sound system, suspension work, brakes, work on the interior...do all of that stuff if you are staying with the cx motor. even with i/h/e you wont feel a difference at all and you wont be any faster. save all your money that you would spend on motor mods for a swap, dont boost that cx thing either. b16's and b18's get good mpg for the power they put out. i just got 330 miles on my last tank, 300 of those on the highway above 4.5k rpm the whole time on my b16.
to sum it up, make the car look how you want it, or work on suspension and brakes, because anything you do to the cx motor wont be worth the money.