you technically have 2 mufflers already, its called a turbo. yea its safe to run straight pipe dont listen to anyone who says you need back pressure when you have a turbo.Ok, i know this has probly been discused numerous times allready, and ive researched it a little bit and never really quite found my answer. I got an 04 cummins (bone stock) I noticed it doesn't have a resonator and cat on the exhuast. All i seen is a big mufflor. I want to take my mufflor off and just run a straight pipe to make it louder. Someone told me i shouldn't do this becuase i'll have no back pressure and that diesels need back pressure. This guy also said it would be safer to just put an after market mufflor on it, but becuase of the back pressure difference the after market mufflor would make i would also have to tune it. Is any of this true? I take really good care of my truck and don't want to do any damage to the engine due to mod's on the exhuast becuase of back pressure. Is it safe to run an open straight pipe, like is it harmfull to the engine. All i want is to make it louder but don't want to cause any damage. Any input is highly appreciated.