ok, welcome blackcobra. first thing you did wrong was post a CAI question in the power adders section. no big deal. power adders refer to forced induction like turbochargers or superchargers and along those lines. CAI is a simple bolt on which would belong in the bolt on section.
ANYWAYS, modding a mustang can be fun and rewarding but there are certain things worth spending a lot of money on and there are things that aren't. CAI is one of those things that you don't want to spend a lot of money on. with a v6 mustang, you will get the same effect with a 40 dollar intake as a 200 dollar one. they will not add but 1-3 horsepower no matter what the manufacturer says according to most people. go to americanmuscle.com and get the cheapest one or ebay. they are easy enough to install if you can change your air filter yourself, you can install one of these.
there is a Ford Windstar upper intake that you can switch out with your upper to get some pretty decsent results from what i have heard.
http://www.stangnet.com/mustang-foru...fold-swap.html
Gears are suppose to be the most rewarding without adding serious power adders(turbo, supercharger, or nitrous)
have fun modding and don't be afraid to ask anything in here just realized that eventually you will get criticism and be laughed at no matter how hard you try to avoid it. it's all good in the long run it builds character. also go through the sections and read the "stickies" at the tops of the sections. you can get a lot of information from there.