Exhaust opinions / Mandrel bent 2.5 or 3" / Input?

Next modification on my Dart Lite, is exhaust.

Currently has single system, that Y off into 2 or 2.5 dual, 12" glasspacks, and crushed tailpipes that rattle and bang on everything.

My local customer will bend me 2.5 or 3" (these are the sizes they can mandrel bend). They will come off the manifold with 2-2.5 and step up at the bellhousing under the car, with a flange so I can remove to fab turbo tubing, and re- install to drive as needed or wanted.

If I go 2.5 I can get the muffler and tip free (vendor rep).
If I go 3" I have to buy the muffler and tip, or I can have it turned down just behind the bumper for stealth look.

I know both sizes are overkill for a N/A /6. However, this car will sprout a turbo over the winter. (Grand National Turbo, Front mount intercooler) I think the 2.5 would work since it is mandrel bent would be OK for the turbo system, but I am leaning more towards the 3" system.
Opinions? Input from some of the turbo guys?