There is no pre-made dash kit for your car... if there was, it'd look like crap.

There is a trunk mounted amp for all the speakers... I believe in the TL it is either on the under side of the rear deck, or in one of the rear corners of the trunk, just inside the taillights... behind the carpeting.

To install a new deck, you'll need a custom fabricated dash plate, and either find a way to send a signal to the stock amp... by using a low-level signal... or bypass the amp and replace all the speakers. The sound gained by just changing the deck, and using the stock amp and speakers isnt all that great. I Highly recomend a complete set-up... new amp(s) and all new speakers... the Bose speakers really suck.

email ron@streeteffectz.com for information on a custom dash mount... he has done a few that came out really nice.