opinions wanted please

I read somewhere on the net that DUAL 2" exhaust will support 400hp.
DUAL 2.5" will support 600hp.
And DUAL 3" will support over 750hp with little restriction.

I personally know guys who push over 1000whp through a single stalk of 4" on turbo 4 cylinders.

Use accordingly.

Back Pressure is overrated. I ran a open headered 360 street car for over a year with no problems, other than noise violations.

IMO, I would do the 3" system now, but I work on a budget and like to spend my money ONCE.