firstly I would check that they are actually baffled. That design of silencer is normally straight-through, with a perforated pipe and exhaust wadding wrapped around it. This type takes out the high frequency harmonics without restricting performance. Replacing with a straight through pipe, would give very little, if any performance gain and a harsher exhaust note.
That's my next question, I heard the megs on idle and its quite a sound. (I'm certain that is how they were original 60's race ready). I guess my next question is if I take out the exhaust wadding/perforated pipe inside the silencer, would it sound like the megaphones? Or would it be different because it becomes a chamber before letting out?
(i did this to a motorcycle ducati dr16, moto gp replica and it sounds like it should, full race sound).
Maybe getting a set of megaphones would probably be easier install job that actually removing the wadding inside the stock exhaust.