rnuckolls

I apologize if this has been answered but I have not been able to find the answer anywhere. I am looking at putting on a new muffler on my 2014 GMC Sierra with the 5.3L engine. I have never done any exhaust modifications before and I do not know what exactly to look for. I know there are different inlet and outlet pipe sizes and different offsets for the muffler. Do I need to get a muffler that matches the stock pipe sizes and the same offset setup as stock?