I have a shaker 500 system in my 09 GT/CS and it sounds ok but I listen to a lot of music and I enjoy good quality drivers when doing so.

I read the Pioneer sticky and went through their vehicle speaker selector thingy. I was a bit confused when it was trying to tell me that the stock front speakers a 6x8's though.

Does anyone have information regarding the different sizes of speakers that are in the Mustang?

 

In the upper part of the door you have a 6x8 speaker. The 6x8 actually consists of two speakers mounted to a plate, a tweeter and a mid-range speaker. Below that you have an 8" subwoofer. The 8" sub only comes with the Shaker 500 or Shaker 1000.

 

Oh, I understand now. I may be upgrading soon.