Sometimes I wish I had a 5-speed, but if you ever plan to take the car to the drag every now and then, be glad you have an auto. Depending what you want to do to the car, I'd go with a KB for more power. I have the Saleen S/C in my car right now and some day I'll sell it and get a KB. As far as the auto trans, I've replace the TC with a 3 stage PI TC and had the trans rebuilt by Tony at Larry's Transmissions. He does mods to these things to make then stronger. He even replaces the input shaft with a stronger one he had made. My motor is still stock and one day I'll have Adam at ST Motorsports rebuild it. Currently I'm doing 421RWHP/409Tq (yes on a safe tune). I have 3:73 gears, some people go with the 4:10s. If you not a big drag racer and you worry about the gas prices, then the 3:73s is your choice.
I use to race my car, but the wife banned me from racing due to the high cost or repairs.
If you have myspace, you can check out my video's there.
Here's an old video with my son racing my 05. The other car has a whipple s/c, built motor, no drag tires and 20" wheels.
All the S197 mustangs in our group are all auto's.
drag strip, st motorsports, FFW, mustang- Video
You can see all my video's on streetfire.