I have the stock 3" with 4" tip on my rig right now, and I like the way it sounds...

How much of a difference will a 4" or 5" make in sound?

What do you guys think sounds best?

Muffler? No muffler?

The cat and muffler are gone and its super loud when I get on it...

 

4" sounds real good on my 24v truck and i have 1 with 5" stacks and its real deep and sounds great... but loud in the cab

 

I recently installed a 4-inch system from Pinnacle Performance (owned and operated by Jerry Jardine - famous for his gas engine headers) and can't say enough good things about it. It's definitely louder than the stock exhaust when I get deep into the go pedal, especially with the windows down, but not too much louder inside when driving it easier. It really gave my truck a substantial kick in performance with the turbo spooling quicker, producing more boost and the EGTs are down about 100* or more. So, I say go for it - you won't be sorry.

Steve