when we say that an engine has forged internal it means that pistons and connecting rods has been forged, witch is a heat and pressure treatment done to give a lot more of strenght and hardness to the metal.
in fact in will last more to heat, boost and even nitrous.
yes theres many forged pistons and connecting rods available for the 3sgte.
Wiseco, JE, Arias, CP, Jun make em, just to mention those