A very limited budget?
You might consider switching to a K&N drop-in (50$) and removing the intake resonator. Some people even report better results with this than with all the fancy "cold air" stuff. I know you have the panel-type filter, but it may still be worth a shot.
Exhaust, I'm anything but a guru. I bought a Borla cat-back, but you might do better with a custom-built system locally, or just replacing your res and stock mufflers with some high-performance units. Dynomax, Magnaflow, I don't know. Search around for opinions. I love my exhaust, but knowing what I know now, I think I could have gotten away cheaper.
FWIW, I started with an ITG open-element foam filter. Didn't notice much difference until I 1)installed the exhaust, and 2) removed my hoodliner. I don't know about power, but throttle response was quicker, and everything felt better.
Since I am also on a "very limited budget," the only other power mods I'm even thinking of are 1) custom Y-pipe (retaining stock cats) and 2) Superchip, or equivalent.