Gears would probably be the best for your price range, for all the reasons stated above. But, if you could save up a bit more, or hold onto it until you find a good deal, I'd think about some gt40 heads and Intake. Do your research on your options, and you won't be dissapointed.
2000 Mustang GT-Former giggle gas addict
1990 Mustang GT w/ Vortech V3
***resident gun idiot***