One additional thing I wanted to compare between the units was the overall design for the X pipe/flow.
The FI exhaust has longer primary tubes that run through their X pipe:
I have not seen pics of the inner works of their X pipe, so this is was it looks like:
Kind of hard to see when looking down through the inlet pipes, but it appears to be a 3 to 4" oval cut opening where the 2 pipes merge.
The Motordyne unit takes a more direct/forced path and the point of merge is about 6-12 inches closer to the cats/test pipes:
YXZpipe merge
Muffler divider
I don't know how each setup differs in performance, flow, or sound, but I though it was interesting to note.