at least a phase 2, you hear a knocking sound that goes away when it warms up.

I don't know if phase 1s have it as these folks steered me away from the phase 1 when I was buying mine.

The slap is caused by the very short piston skirts fitted in order to lower friction and keep emissions low.

I understand not all of them have it, but every darn one I have heard does.

So piston slap is essentially knock, or is it just a thrashiness inherent in 2.5 motors? My 2.2 never sounds like that.