Well you can do what im thinking of doing. Get Flowtech LT`s and matching x-pipe for under 400 bucks and throw them on... Same style as hookers so they will go around the transmition...
I know a guy with a 99 gt, with flowtech LT's and X pipe. With all the bolt ons and Drag radials he's run a 12.80. The Flowtech LT's make good power. His is a 5 speed. He's also a good driver.
For an Auto, I still think a high stall Torque convertor with a cooler, is a must for good 1/4 mile times.