Be interested on opinions about installing speakers in the rear cockpit kick panel as well (under the back seat). Think I saw a boat with a set in this location. Only drawback I see so far is that they may get "kicked" regularly, although my 190 rear speakers survived down near the floor, just took a little abuse.
Regarding the tower cans. If you pull the big driver, you'll see that there's an additional ring screwed in there and the holes are slotted, looks like some adjustability there, not so much on the tweeters though.
'06 X2 MCX
"I understand why some people may not want to do this the way I have recommended but I can't understand the death grip some people have on a toilet plunger with a hose fitting." -JimN