Well then, you already fucked up by putting a spoiler on your car. I'm sure just from this post you have minimal knowledge and probably bad taste so it's probably a big ugly aluminum wing. But I'll be the one and only to put that aside.
Do some research, the b18b1, LS motor; has lots of potential if you go the forced induction route. I've put that motor in all of my hatches. My turbo LS made a respectable 253 HP.
There are so many options and I suggest you do a little more research.
You didn't give any type of power goal or your budget so even if I were to give you more info, I couldn't tell you much without that.