well typically u measure the depth before buying the products, but in ur case, it's too late. hmm...well in order to take out the basket u need to remove the entire door panel. if u don't kno how to, check out MorningZ's site:
MorningZ's homepage
Just remove the basket and put ur mb's face to face with basket and see if it fits. I'm pretty sure you're going to cut the backing of it. I just use the blade of a saw and cuz it out. It was pretty easy. Don't need to make it fancy. Just as long as it fits.
If you want to see if the mounting depth fits, just remove the basket and stick ur 6.5 in there. Have your windows down first. If it does hit the window, just go get some other brand. I kno Infinity 6.5 fit.