Hey guys and gals I'm new to the forum tonight and got my first diesel a month ago!!!:drool2: so forgive me if I ask slot of stupid /simple questions in just trying to learn as I go here. I have a 05 dually auto 62k with a afe stage 2 intake and I'm looking to add an exhaust for my next upgrade. I use the truck as my work truck . And I own a transport company so I want to keep it reliable but fun to drive. I was wanting to go with a 5" straight pipe from the turbo back but then someone told me that 5" was for motors over 500hp??? Does that sound right?? Should I go with a 4"???? I'm looking for that throaty mean sound and I intend to put either a smarty or a EFIlive on the truck eventually so which way should I go on the exhaust???? I'm all ears like I said earlier I'm new to this and open to any input!!! Thanks guys!!