It depends on the four stroke AND the 2 stroke you're comparing. I'd say a 52 four stroke might even be comparable to a 46, if it's a 46 LA.

Four strokes used to be considerably less powerful than 2's. But over the past few years, four strokes have gained and gotten relatively close to 2 strokes. (Hence, Woodsy statement comparing his 48 to his 40.)

It will also depend on the aircraft it's going into and the performance you're looking for. ie. I'd rather have an OS 48 four stroke than a good 46 two stroke in a Cub or a Taylorcraft, but not in an Extra.
Dennis-