Well, something boost related is definitely the right idea, but the budget might be a little bit tight to do it 'right'.
You could take your pick of forced fed goodness, but you have to remember the supporting mods. Fuel and air flow are the most important, and ignition is in there too, especially with the better factory flow of the cobra over the GT.
Beyond that you should think of your driveline. How long is that drive line going to hold up to boost?
Not to discourage you, of course, but sometimes it's better to make sure you can put the skinny to the floor and not worry in the back of your mind that something is going to break.