The OEM exhaust on your 2009 should be full 2.75". If the member you told me of has a white 2010 supercrew, he has the 18" body. All Magnaflow bolt on kits come with 18" bodies. The 14" will be about 20% louder, it isn't drastically louder, and isn't too much louder inside, but it gets the point across to the people outside thats for sure.
I would get a 3" inlet/outlet 14" body, you will like it. Part #11229