Nitrous wont put any more pressure on the bottom end than anything else that increases the airflow in a motor would. And an extra 15-20 HP per cylinder certainly wont break cast pistons if there's no pinging going on.
You won't hear high speed detonation while going down the track. Pinging is one thing, but high speed detonation leads to melted pistons, blown head gaskets, pounded rod bearings, etc. By the time you hear anything while running nitrous, the damage will be done.
Plus, nitrous is an instaneous 150 extra HP, whereas a naturally aspirated motor will build that HP more gradually, for lack of a better term.
Go ahead and squeeze it. If you melt or break a piston, it's only a 318. You can put in a built 360 then. ;-)
