As far as I know, I don't think there is much you could do in terms of bolt on that would make your car fast. And if there is, it'll probably be too much money to invest in that motor.
I'm in the same boat as you are, (DX auto) and I haven't really done much to the motor. I've always wanted a swap but it seems that my car is getting too old to do any worthwhile mods anymore.... :happysad: