Does anyone know if my exhaust will get any louder if I take off the cat and leave the DPF? Will it cause the DPF to throw codes?

 

You'll need some sort of pipe / sensor in there in order to keep from throwing codes. I don't remember who makes it, butI someone out there does.

 

Why would you want to remove the cat and retain the DPF? The cat burns the unburned fuel (remember the extra fuel from the regen cycle), which raises the temperature of the exhaust, which in turn burns the soot out of the DPF. Without the cat your DPF would get plugged full of soot in no time.

I understand that if you remove the cat and DPF the exhaust gets considerably louder. The muffler on our trucks is a straight-through design, more like a resonator.

 

So basically, there is no way to make my exhaust louder without removing them both. Nice. Way to skrew us all EPA.