thanks for all the posts this is helpful, I looked at the rear speakers and it looks pretty easy to replace the rear speakers without removing the windows, as for the head unit I am planning on doing the job this weekend i was going to buy a pop up screen but the gear lever seems to be to close to the head unit to have a pop up screen
but I found a pair of custom subs in boxs designed to fit behind the seats but they were made for a 996....didnt know if they would fit into the 944 but thought it was a good idea, once again thanks for the help, will post with either my success or failure