I am in the process of replacing the front and rear speakers in my 2013 Mustang with JL C2-570X speakers. I just test fit the rears and quickly discovered that they were smaller than the factory holes in the deck. I then measured the stock rear speakers and discovered that they're actually 6X8's. I have been searching online to see if I can find a pair of 6X8 to 5X7 speaker adapters and can't find any. It looks like I am going to have to have some adapter plates fabricated out of MDF board in order to seal the outer perimeter of the 5X7 speakers. What is everyone else doing to get around this issue when installing 5X7's in the rear deck on their 2011-2014 Mustang?

 

5x7's will fit perfectly without modifications. I know as I've replaced my back speakers with 5x7's. I have these installed.

 

Yes they do fit, but the JL speakers have a gap around them due to the factory speaker hole being a true 6X8. I am **** about this type of stuff I and have to have the entire hole filled up just like the factory speakers. I heard they the Infinity speakers are a true 6X8, so maybe that's why the fitment is spot on for you.