Rusty is correct, I was referring to the sound levels in the cab. You would be surprised how much of a difference in sound levels in the cab this makes.
To get the noise level in the cab lower with exhaust that is in the stock location, raise the height of the exhaust. You would be surprised how much of a difference this will make as well.
Larger exhaust diameter will change the tone. I personally find the lower tone to be easier to deal with. So the 4" size change helped me in multiple ways.