Next performance mod

Hey I just got my car about two weeks ago its a 98 Black Civic EX

and I already have intake and exhaust on it. I was wondering

what the next thing I get for it should be. I was also wondering

if there was anything that I could do myself that is cheap and will

give me a few horsepower. For the mod i dont have much to

spend only like 100 dollars or less. Let me know what you think.

Thanks

-Jake