From a video I watched for a BavSound speaker replacement video (below), the dash speaker, the one above the ski passthrough, and the rear/side are super easy to replace, and the door speakers are no big deal. I've read though that the subs behind the seats are a tremendous pain in the ass that requires disassembling a bunch of stuff to get to them. The
BavSound Stage One replacement speakers are all direct replacements for all but the Sub and the kit runs $797.