Ok do you use a lot of salt? Wrap it or leave it uncovered in fridge?
What's the purpose of leaving the fat cap on?
When I do my Pork butts I trim all the fat off so I can get more seasoning to the meat cause I throw out the fat anyways.
I used Montreal Steak when I was competing. I'd start working on the brisket as soon as we got set so that I could have the rub on, uncovered, for as long as possible prior to putting it on the WSM.
As far as the fat cap goes, the general consensus is fat cap down. It tends to act like a moisture barrier, keeping more of the moisture in the meat instead of it dripping into bottom of your cooker. There are several YouTube videos around giving tips on how (and much) to trim. Watch a few, then you decide ! ! !
BD