For what it's worth, my non-comp stinger TNT v3 has a nominal OD of 2", and the wall thickness is just whatever the stainless sheet metal is, so ID like 1.9" roughly-ish 48mm. There is no second inner tube on the stinger like on a PFP.
My understanding from talking to Tim about it (briefly) is that the comp stinger is the same diameter it just extends into the belly of the pipe a bit.
So it's a big stinger diameter, comparable to unmodified B-pipe.