So, I adore the BOTI effect... but I also adore shaders... and we all know that BOTI and shaders go together like oil and water.
But, when I turn off BOTI, the inside of my TARDIS (from the outside) just looks like... well... the inside of a police box. not very immersive.
my suggestion is to replace this plain, Policebox looking interior with nothing but black.
if you think about the TARDIS model, made up of shapes, all Im asking is to add a black slab along each side of the inner of the exterior
So that it doesnt look like this,
It should look like this,
See? this gives the illusion of it being bigger on the inside, without actually needing the BOTI effect. it would make a lot of sense on for the DMU as well, considering that BOTI is disabled in their anyway