lol. Bro, BMW stealerships install Dinan products. Period. So...yes... they work directly with BMW. Try to get the stealership to install your cruddy JB4.
They are expensive because they are the only tunes sanctioned by BMW so there's a price to pay. JB4 is a Great Choice if you want to remove the tune prior to getting your car worked on every time so you don't void the BMW warranty.