New to the game

I've had almost every item you listed done to my car and next to the super charger the gears made the biggest seat of the pants difference. My exhaust upgrade made a noticeable difference but only under the hardest excelleration , and really only on the upper rpm range (I'd say an entire exhaust system is almost the least bang for the buck upgrade, at least on my '00 GT, however I think just new mufflers are one of the best upgrades because the car sounds great with them, and for only $200 installed it's about the cheapest for making a real noticable difference in your car, not necessarily performance difference though). Gears you feel all around and under all driving situations. I really think it is by far the biggest bang for the buck upgrade you could do. I really come close to saying I get almost as much fun from the gear upgrade as my Vortech upgrade (almost, but not quite, and the two are a wicked combination). Good luck!