If i were to do all those mods:
-AEM Cold Air Intake
-DC SPORTS HEADERS
-and some sort of full exhaust, prolly custom 2 1/4 piping with an arospeed muffler (SOUNDS AMAZING)

How much power should i be gaining?
Roughllyyyyy speakking of course.
Thankss

very very little

Compared to the amount of money you put into that, not enough.

roughly about 10-13 hp. with the intake and header you will feel the difference in bottom end power, meaning torque.

What else can i do to make it faster?
besides those things and without forced air?

Gude package will get you an estimated 40hp to the wheels(approx $1500?)... or you could go nitrous. Nitrous Express makes a good kit for our cars. With the tricked out kit(bottle opener/heater etc... about $1,000 I think) Although with these you can increase their benefit by having the intake and exhaust done up nicely.
-Numinous

whats a gude package

Go to the top of the "products and parts" forum page and type gude into the search box and click on search. There are a whole bunch of threads on Gude.

Some of the reports are bad and some are gude.

you won't be feeling too much...well at least a little..probably 10 -13 on da wheel..
nos would be the fastest way..and easiest..to get hp from that..
wait for turbo..