No nitrous... no turbo.... automatic tranny... only bolt ons... Wow... you're really limited to your possibilities. Maybe you should consider "bolting in" a new motor?
Oh, you said something about a KA24DE and then said something about 1.6... You seem to be confused about what motor you have. The 1.6 is actually a GA16DE. If you had a KA24 you wouldn't be to worried about the stock power, it's quite a bit more powerful then our measley 1.6's.
If you want a more powerful motor, you'll need to save up at least $4,000 for parts to perform an SR20DE swap. More powerful motor, much larger aftermarket.
However, if you just wanna keep your 1.6. I'd recommend a Cold Air intake from HotShot. You can get one from
Liuspeed, it's in the B14 section. It's been proven to add like 5 horses are something. You can also get an underdrive pulley from him.
Just so you know, the 1.6 has been proven not to make a lot of power naturally aspirated. But with a turbo you can make her decent.