what to do next?

Get Maximum Motorsports Full length subframes. These are some of the highest quality suspension parts that everyone seems to recommend. You will want to ahve them welded in for you, just bolt them up, and take the car to a local muffler shop and they can do it in like 20 minutes. I would do these, and the gears. If you ever plan on getting a chip then dont get the T/A because it will be void if you do. Good luck

You could get all those items with $500 but probably not have them installed.

For your year GT there are no bolt-in subframes. I would suggest steeda full length sub frames. They are descent priced and nice. I have MAC ones and I bought them because they were cheap at a local shop. Cost me $65 + $130 for install.

Gears are in the $150 range for FRPP but I have motives and they were $128. Then depending on miles determines which type of install kit you need. I bought the full deal even though I have low mileage just to be safe.

The T/A you could do yourself if you have mechanically inclined.

You might be better off getting a diablo tuner or other type because then you dont need the T/A and you can correct your speedo for the gears.

Also check out ebay and the classified sections to maybe get some deals on used stuff like T/A, pulleys, tuner, etc.