Torque Converter: The core of a traditional Automatic tranny, the Torque Converter does just that. Controls the torque output from the engine to your wheels. Why do you need one? You don't have a clutch to control the car going into and out of neutral, so you need a TC to control torque output to prevent the car from stalling, jerking around a lot, etc. Torque Converters are also what helps Automatics 'launch' by using the brake like you'd use a clutch in a manual. But instead of revving in neutral, you rev in gear while the brakes hold down the wheels. You let go of the brakes and the wheels go. Simple. But you're limited as to what RPM you can launch at (that's how far it can load up with torque, it's capacity). This special RPM is called the stall speed of a torque converter. You can also identify it by rolling along in gear, and suddenly giving it gas. You'll see the RPMs rise really quickly to the stall speed, and then normally afterwards. An Aftermarket Torque converter will have higher stall speeds letting you launch better, and letting the car respond better in the lower rpms. Currently, the stall speed of the stock Celica converter is 2000rpms. Another performance blow is that the torque converter in the Celica is actually, if not the same, then based off the Lexus IS300's converter. Why is that a blow to performance? For one thing, the IS300's TC is tuned for more torquey cars. Like 200+ lbs/ft. kinda torquey. The Celicas have no more than 135lbs/ft. This results in a sluggish low end which didn't have much punch to begin with. For performance, you want a converter that has a higher capacity, which can churn out more torque. This means a higher stall speed. Even 3500-4000rpms would be reasonable for performance if you consider there isn't much torque to begin with, and what little there is, is made at a high RPM. This way the TC can build up more torque and get you into the powerband quicker. Keep into consideration, normal everyday driving. Tapping the gas and jumping to 4000rpms isn't really smooth, what the stock transmission was meant for, so you should know beforehand whether you want to make a compromise between performance and luxury.
fix your 2000rpm Torque Converter with thishttp://www.levelten.com/store/import/items/converter/ja315_5000_toy_lexus_fwd_converter.htm
after this you'll have a 3500-4000rpm launch!!!!!