Maybe you should take a few engineering classes & build a few race engines like I have & you'll see how long a cast aluminum piston lasts in a forced induction application... especially when pushed enough to make a "target" 625hp when starting with 11.8:1 CR like the other poster said.Also, even if the TRD kit makes 625HP (which would take around 8-10lbs of boost), how long do you think the cast pistons of an 11.8:1 engine like the 2UR-GSE in the IS-F will handle that?
First of all,TRD would not put something in that would damage the car!It would have to last just as long as the vehicle's warranty and thensome.
Second of all, the pistons are made much lighter and stronger than any of the other IS'S including the IS300 which has the famous engine in it borrowed from the Supra.Maybe you should attend a training class from Lexus on how this car is built, they will explain everything to you and I'm sure you have more knowledge about this car.I work for Lexus and attended these classes and was amazed myself at how much detail was put into making this car, alot of parts are made of Titanium and aluminum and are built to last!
And yes, I've seen the titanium intake valves & forged crank & rods. Nice...