is there much difference in the perfomance of a 4" exhaust w/o a muffler compared to 4" w/ muffler? and how much better is it than 3 1/2" w/o muffler?

i have the stock exhaust on my new to me 01 duramax and i just put on airaid intake kit. i havent decided if i am going to get a programer yet but it is a good possibility down the road.

thanks brian

bfoster129,

Depends on the muffler, if it's well designed it won't matter, if it's one of the "no packing" mufflers it will make a difference etc. We pack all of ours with a ceramic blanket and stainless steel wool.

Mark @ DPPI

Truck will be louder.

Only real benefit would be in keeping your EGTs down (exhuast gas temperature)

My thoughts.........