a buddy of mine just bought a 93 four door too. he just threw a tubo on the stock motor, it made a big differance. haha but i hear thats not the right way to go.
i just swapped a d16y5 V-tec into my 92 4-door and its decent, but i hear that the b18 is a way better swap. i'm pretty sure you can find b18's in integras, so look around
if you dont want to motor swap, then i guess just go for full intake and full exhaust, probebly wont do a great deal though