Overheating a pizza stone? I bought a pizza stone without realizing that the max temperature it would withstand is 450 F (according to the instructions). My oven goes up to 550 F, which is the temperature I'd rather bake my pizzas at–is it OK to overheat the stone for the sake of the pizza?
As always, it comes to the meaning of "OK". The most likely scenario here is that the stone's life is shortened and it cracks. It's impossible to say when this will happen, it could be soon or it could stand up to hundreds of pizzas. 

So if for you it is worth it risking the stone, you can do it. If you want to avoid with certainty the stone breaking after 4-5 uses, don't use it outside of the parameters determined by the manufacturer.