As far as performance is concerned, a higher stall torque converter is easily the best mod for an auto tranny and will considerably decrease the 60'.
SLVCELI is right though. It will be expensive to buy and install, and you could either completely upgrade your suspension or put it towards a manual tranny.
As for whether it's pointless trying to race an auto...sure it's pointless, if you're trying to do it competitively. If you're just doing it for fun, then why not? I raced my auto GT last weekend, sure it was an adrenaline rush that lasted a full 17.06 seconds, and I was forced to race against someone who's engine was almost 3 times the size of mine, but I had fun.
If you're made of money, go ahead and buy one...but otherwise there's plenty of other things to spend that money on, and believe me you don't need a new torque converter to have fun.