Exhaust Pipe Diameter 273

Just wondering what size exhaust piping I should be running behind a stock 273 2bbl. Been wanting to do a dual exhaust system for a while from the manifolds back. Thoughts on H or X pipe? Is it even necessary with a stock motor like mine? Undecided on mufflers too, any suggestions would be appreciated. Thanks!

Whatever size your collectors are is ideal however that isn't always possible.

X pipe over H pipe but it isn't necessary but will yield you multiple gains over a straight dual system.

Mufflers...anything but flowmasters will be fine.