I had the rear subwoofers replaced with 2 ohm 6 3/4 Kickers. Found a shop near where I live called Electronics Depot Car Audio at 1240 W. SR 436, Altamonte Springs, FL (407) 657-1010 for anyone living in the area. They did the job quickly for well under $400.00 tax included. The dealer wanted $1,300.00 and another audio shop wanted over $400.00 before tax. Very efficient and thorough and they have worked on Xfires before. They also do mechanical work and I am having them check out a fuel related issue as they have the scope to run the test. They also repair MB vehicles and have the parts. So if you live in my area I definitely recommend that you check Electronics Depot out.