I just put a new shower in our master bath and the shower has a P trap plus a vent inside the wall going up through the roof.
Sometimes the Wife comes out of the bathroom asking why the empty bathtub (also with a P) goes "GLUG" when she flushes the toilet.
I told her she is overloading the toilet.:D
Hint:
right before you put that pan in for the last time put some quik set mortar down under the part that doesn't touch the floor for support.
Otherwise the pan can crack because they are not made to support a couple hundred pounds.
