Well I got my 2000 bone stock right down to factory exhaust. I didn't intend on doing any mods other than exhaust for sound but ended up doing some more things than I intended on doing when I bought it. I kept everything I upgraded just in case I ever decided to sell it.
I've got plans for forced induction by the summers end. If you want easy HP on the cheap nitrous would work as mentioned above but getting blown would be a better option IMO save your money on the expensive mods that won't get you very far and build on things after you install your choice of forced induction.
Blower, a good set of Blower cams, long tubes with full exhaust and depending on what Trans you have gears and don't forget about a good custom dynoed tune.
All of which will set u back a few thousand...