3" pipes or 2 1/2' with cutouts?

Locomotion said
The 2 1/2" tips would be a choke point.
But don't some companies make OEM style tips for bigger pipes?

Way back in the day, I took a set of factory 340 tips and cut them at the point were they measured 2 1/2" (hope that makes sense), then had them welded to my 2 1/2" system.