Is anyone well enough versed in exhaust systems to answer this?

I've got a 1990 Carbie Magna with an EFI exhaust system (i.e. Extractors with an O2 sensor that isn't used) and the single cat directly under the body about halfway along, with a small muffler near it as well as the rear muffler at the very end).

I'd like to put in carbie-type extractors - i.e. the ones with the curly hot air pipe that feeds some exhaust gas back into the air filter through that one-way valve. But the carbie extractors have different joining points (and pipe lengths) than the EFI set.

Can I cut the pipe roughly at the same point where the EFI extractor head main pipe would connect to its next second stage, and weld a flange on at that correct position? Or do I need the full carbie exhaust system up to (but excluding) the rear muffler? I'm sure the rearmost muffler, as a fairly small unit, is compatible with both types of systems.

What I mean is, can these things operate on a mix-and-match basis, or should they be installed as full piping systems (bar the rear muffler)?

To the MODs - please close off this thread.

I asked at two exhaust places today about this. You can mix and match sections, but there is no benefit to fuel efficiency or power by having the EGR pipe in the extractor headers. That was just a pollution reduction feature with no practical benefit other than that.