Um.. yeah.. 2 inches is not going to do it. 4 inches is more like it.
Itīs hard to get 12" in a WO and i donīt think 15īs would fit like a glove either.
The WO is designed for 10" and 8" woofers from the beginning, and all other
attempts to put larger drivers in it is all experimental at best from other builders.
Some with good results some with bad.
I recommend you to draw it up on a big piece of paper to se how small the space
actually is for the woofers. And from there try to fit the 15īs with
a papermodel of the sub, 2D.. not 3D