levelten has shift kits and torque converters that will be one of the best upgrades. A torque converter will probably be one of the best upgrades...not only will it shave down your 1/4 mile time, but it will allow you to get more power from other upgrades due to lower drivetrain loss. With a tranny cooler(other then stock, yes you do have a stock tranny cooler) the next big upgrade would be a turbo. Dont forget though a auto ls runs about a 16.8 stock and with bolt ons and a torque converter upgrade you would probably still be in the low-mid 15s, which is what a stock/CAI gsr would run.