Did you read it?
Crawford: 400 whp. There are no internal engine modifications needed at this power level. The car would need a larger turbo, intercooler, fuel injectors, fuel pump, AOS, and retune of the ECU.
AMR: 400 whp. We suggest a set of forged AMR pistons and billet rods to safely boost up the engine.
Yimi Sports: 400 whp. For an EJ205, you should be doing a basic build on the block that would include forged pistons, rods, good bearings, and head studs. Obviously, quality machine work and tight tolerances/quality control are crucial. For an EJ255 and EJ257, all the block needs is a set of forged pistons. 400 whp (particularly on 91 octane pump gas) is when cylinder pressures are high enough that a random knock event can take out the stock pistons. The rest of the internals are more than up to the task.
My tuner says 350ish is where you need at least pistons. Because like stated some bad knock can kill a piston pretty easy above that range.
378awhp/373wtq Custom Dom 3 & CBRD tuned 2006 STI.
"When in doubt...flat out" - Colin McRae