What can I do to improve my mustang?

I currently purchased a 2000 ford mustang. Pretty much completely stock vehicle except for the rims that were on it when I got it. V6 3.2L. Standard transmission. I would like to know what mods I could put on it to make it a little more efficient speed wise, and I really want it to be louder. I know generally what I need but have no idea how to pick the correct stuff.

Not looking for anything like "replace the engine" or stuff that will cost me thousands. Not made of Money but not exactly a college student either. I'd say keep if $300-$500.

Change your gear ratio, a programmer, CAI with a heat shield (don't like stock intake looks), throttle bodies, new mufflers, headers, H/X pipes all cost below $500 individually. Best bang for your bucks is going to be higher gears as it will increase acceleration off the line, making it look like you have more power than you actually have.

If you want to make your vehicle louder and get some powerful sound, you need to change your muffler. The Flowmaster muffler is tuned for maximum performance. It is also made to make your Mustang sound deep. This is a high quality item and Carid offers it at a pretty reasonable price. Follow the link to see details.