LMM Exhaust Question

[cajun225]

I know this may not be the correct forum to ask this question sorry.

I just traded my 08 LMM in for a 10 LMM and now doing upgrades to it. My question is should I run 4" or 5" exhaust. I use the truck everyday and pull my 15k rv about once a month. I am having a custom tune done for mpg and hp. Max hp will be about 530 to 550. Thanks for the input.

[Mitco39]

Only difference between the two is the noise. 5" will be louder. Not much performance difference as your still pushing it through what I would assume is a stock downpipe.