What do you want to improve? I rather enjoy the 40mpg I get in my hatch

If you want to go mini-me (VTEC head on that motor) I really think you're wasting your time. I'm assuming you want more power so in all seriousness, sourcing a different motor would be your best bet. d16z6 or b18a/b would be a very cheap solution. Just my 2 cents.