Someone Please Clarify

You can't make gross generalizations like that. No one can sit here and say "the pistons are good for this much" and "the rods are good for that much" power. It's just not that simple.

There's 400 proper, reliable horsepower, and there's 400 bad, dirty horsepower. Bad tune, too hot, too lean, whatever. My point is that you will easily see someone pushing 400hp very reliably on the stock bottom end, while at the same time, you'll see some fool who blows his up while making only 350hp.

I will say that with a proper build and tune, the bottom end will easily hold 400-450+hp. Don't know what you're doing, and you can blow it up at 350.

With a proper build, as the power is increased, the powdered rods will be the first part to go. Replace the rods, and the pistons will be the next weakest link. Replace those, and the crank will be the next part to go, followed lastly by the block.