Aftermarket Radio Help
 

I recently purchased an 03 boxster S. I had XM in my old car and can't go without it. I want to put an aftermarket in-dash system in, because the XM gets really clunky with just a car unit for my INNO. I also was wondering if anyone has put the XM navigation traffic system in their cars, because it might be worth the money here in LA if it is as good as advertised.

Does the XM traffic system tell you the best route to take based on realtime traffic conditions or is it a portible mapquest... kinda like my sidekick2?