I have a '91 saturn SL that makes 85 hp. it is slow as all heck. Usually, when I drive, I just floor it, and shift at 2000-2500 until I get to 5th gear...
however, before, I realized that my car was not MEANT to go fast, I would shift between 4000-and 5000 and it was still really slow. I decided I would hook it up. I got a few magazines, and looked around for parts. I realized that an AEM cold air intake was 150 bucks plus, an exhaust was another 200-300 for a decent one, and on top of that I didn't know how to do any of it, so I had to pay labor! before i knew it, that was like 600+ dollars down the drain for 10 hp.
and that was for a car that actually handles well, and could put the hp to some good use.
Its not worth it on a truck, and since you are 16, (no offense) it is probably an old 4runner. it probably doesn't handle very well. it is most definitly not worth the cash.