Ok... I want to put a Flowmaster 50 SUV muffler on my otherwise stock exhaust system. My truck is a 2005 F150 Screw 5.4L. I know I have 2.5" stock pipe... but do I an need offset in/center out muffler, or offset in/offset out?

Looking under the truck at the stock muffler, it looks like there is a slight offset out (it is definitely not true center). I can't tell which one to get.

I've searched and couldn't find the answer, and would appreciate the knowledge. Thanks in advance.

Will