I used the Walmart Everstart maxx 94R as well, everything is in the same location, except it was 1 1/2 inches shorter (lengthwise) than my OEM battery. this wasn't a big deal becasue the metal screw post with black plastic foam can be moved over this exact amount (there are several predrilled holes for the screw). Battery works great, car runs fine, no errors or codes. Plan to register as soon as I can get a Bav Tool.
Thanks for this DIY, it's just a battery, but on a bmw nothing is "just" anything.