So, we meet again, eh Chuck? Thanks, once again, for taking the time to try and educate my dumb <you know what>.
You're absolutely right on the emissions concerns, but my guess is the EFI ought to keep it a lot cleaner that a carb would have. So my 2.5" duals sounds okay, the Magnaflow mufflers shouldn't be introducing much back pressure.
Does mandrel bent pipe vs. regular crushed type bends give much noticeable benefit?