I have a 2007 2500 cummins. It has 4 inch turbo back exhaust at the moment and I'm getting ready to change it to 5 inch. My question is why does it seem to start running hotter than normal when I pull a trailer. Is it because there's no muffler? I'm trying to figure out if I want to order a muffler with my 5 inch kit or just stay with turbo back. It has an efi programmer on it and a few other mods. Any help would be appreciated

 

You did delete the EGR right??!~

 

It is fully deleted