To be honest, the mods you will feel in order go like this:
1 - Turbo/SC
2 - Headers
3 - Cat-delete pipes
4 - Cat back exhaust
5 - Intake Plenum
6 - Cams
7 - Flywheel
8 - etc, etc... this list can go on forever.
But yeah, for a starter mod, if you dont happen to have the 5-7K lying around to turbo or supercharge.. I'd go with resonated test pipes and a simple JWT pop charger. Then, move on to a cat back and a plenum. Try to do intake/exhaust mods at the same time. They will work better together than they do alone.