first off, are you mechanically inclined? if so, id do the following mods in order:
1. catback. i prefer
flowmaster but listen to a few sound clips on
www.mustangexhaust.com to pick what setup u like first.
2.
BBK ceramic coated Long Tube headers and a shorty X-pipe to go with that.
3. gears id go 4.10s if its not gonna be driven on the highway
4. u/d pulleys, easy bolton and worth about a tenth in the quarter
5. TIRES! traction is the most imp. thing to make ur stang fast, if u can't hook now theres no point in adding more power. if its a daily driver id get some Nitto Drag Radials for the rear.
6. with the rest of the money id actually do an AOD to t-5 swap. u'll be much faster with the manual especially once u do heads/cam/intake.
if anything i mentioned confuses you, PM me about it and ill try my best to explain, i once was in your postion and had no idea what to do. your doing a good thing by coming on here and learning, thats the first step and ur already there.