Magnum 5.9/Doug's headers--what diameter exhaust pipe do you reccomend?

Stock "Magnum 300" with dual plane Mopar intake manifold, Demon 650, Doug's headers...looking at heads/cam next year.

I'm having a custom system with an H-pipe being bent up now...What diameter exhaust system would be best for street (and occasional strip) use?

I assume that "bigger is better" when it comes to motors like this...so forgive me if this is another dumbass question...but I massively appreciate the expertise of this community and my budget only allows me to do this once. :D

Thanks!!
-Mike