Does anyone know what's the best way to launch an IS350 at a standstill? Standard? With the extra power on? Brake-torquing?

ECT PWR will give you better throttle response, but ECT Normal actually gives you higher RPM shiftpoints and is therefore faster if you're going the distance. Somebody more technical than I posted a chart before demonstrating this, try searching for it.

Ah, i see. Any suggestions if the trac control should be on or off?

Experiment with taking the traction control off and feathering it off the line until around 20 or so, then nailing it down. Flat out going wide open from a stop will just get you sideways if the TRAC is off or bogged down if the TRAC is on. Gotta find that happy medium to at least get the car rolling and then drop the hammer.

The best ET I managed using Dynolicious was a 13.3, and that was with TRAC off, going about 70% or so throttle off the line and smoothly applying full pedal at around 20 mph or so.

If only I could get the Supra to hook up off the line.

If you do launch your car, do it in automatic mode instead of paddle shifting cause the ECU shifts faster then you can. Plus its faster in automatic, and warm up your car fully before attempting to do this, cause you're probably going to redline.