Cab Chassie Exhaust question ?????

[ASchuerg]

Does anyone know of a turbo back exhaust that works on the cab chassie w/o giving codes?

 

[HBarlow]

I wouldn't be afraid to alter the exhaust system after the dpf, I don't think after the dpf will set codes. But why? It's already 5" and nothing from the aftermarket will make it run better of get better fuel economy because the size is completely adequate for the engine at it's design power rating.