Your best bet would be a B&G ECU tune. You remove your ECU and send it to them (Or send one in from the same year Libby) and they remove the torque management, and tune your ECU for some pretty good gains. They can also tune it for your specific mods. I think it costs around $400-$450 for the reprogram, which is easily the most bang for the buck on these engines.
Also, Hypertech just came out with a hand held tuner that claims +24 HP/TQ on premium fuel, and has some pretty good dyno graphs to back it up. The upside to this is that you have a lot of options on the actual tuner itself, but I don't think that it removes the torque management which is what kills the performance of these engines.
Pair either of these with a good intake setup and less restrictive exhaust and you get a bit more power to the ground. Also, if you want you can get a performance torque converter and a shift kit to make your auto ****** shift better/faster.