If you just want to get a little more out of your car I would do these first,
1.get a CAI
2. get some new headers (there is group buy going on right now for some Kamikaze ones)
3. get a new muffler
4. replace plugs and wire (Magnecore 8.5mm wires and Denso Iridium plugs)
5. do as many free mods as there is.
You should be able to do all of this for under $1000. You will notice a big difference when driving your car after doing all of these. As far as where to find this stuff take a look around at previous posts. A great feature to use when trying to find out info is Search. If you can't find what you are looking for after doing all of this then post specifically what you are looking for and I sure someone here will be able to help you out.