Will a 4" exhaust give me much on the deeper sound side of things? I don't have much on the mods side, and may or may not in the future. However, I've got an opportunity to pick up a 4" system for pretty cheap. I believe mine in the factory configuration is a 3".

Also, if I run the muffler on a 4" system (the correct way), would that reduce some of the loud industrial sound (which may not be a bad thing).

 

I have a Silverline 4" turbo back with muffler, it has a throaty sound on acceleration. The muffler is small compared to the original,
But it sounds pretty close to the OEM exhaust to me when I am it the truck at cruising speed.
Go the their website and they have soundbite videos you can listen to of a 4"
turbo back.

 

I find that your air intake system also can have a big affect on sound.