do i need 2 exhaust filters on my diesel for emissions

All modifications will have to conform to the emissions standards for your year truck. All the parts would have to be smog legal and you can't delete any parts. I suggest talking to a good diesel specialist to find out exactly what you can and can't do in your state.

your 2008 2500 has one Diesel particulate filter (DPF) The other one is the catalytic converter. Your stack can go directly behind the emissions controls. This will eliminate the muffler resonator and piping to the rear of the truck. There are delete kits available for your truck but all of those would require a programmer of some sort to delete the DPF and CAT monitors from your engine control computer. Deleting emissions equipment is illegal in all 50 states.