Here's the old Mopar Muscle artical where they back to back the old 3" 20" case Hemi muff against the new ultraflow. You can see a cutaway where the Hemi is clearly 3" all the way through.

http://www.moparmusclemagazine.com/techa...ents/index.html

Interestingly they compared the 20" Hemi Case to a shorter 14" case Ultraflow which really isn't 'apples to apples' in terms of size....backpressure or obviously weight

I know the old Dynomax used to be owned by Maremount (which now make the Cherry Bomb Line) but maybe the new owners (who also own Thrush) sold us out and now go a smaller/cheaper route?? That's a real shame