I have a navi tl 06 m/t, I have been having problems with my navi and radio. So I've come for help, if you had you choice what would you put in your car. I pretty much going to change everything, from the door speakers, to the subwoofer, and probably a box in the trunk. Even a aftermarket navi......so tl owners break out those ideas.....pics coming right after.

 

Fix your headunit then upgrade everything and I would not do a box in the trunk. You need to look at some build threads

 

Ryder, do a search in this section. There's a lot of ideas here. Just go thru a bunch of the pages in this section and see what others have done.