"H-pipe," X-pipe," or no pipe?

gumper said
I've battle tested open headers, x-pipe open and x-pipe with mufflers. X-pipe with Flow 30s ran the same ET as open X, and both were quicker than open headers. I have also seen other guys get a significant power increase from those extension pipes, but I've never tried them.
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It would be cool if you could post some specifics of the differences (et/mph) between the systems. I assume the car under test is the Duster with a 408? Thanks.