There was a "learning" process I went through with the side exhaust experiment. It sounded good at the time to try it, less plumbing and hardware. They worked ok but...#1-The Kawi style above the bond line was LOUD and spewed black gunk down the side of my boat (I had serious motor tuning issues).# 2-The 2" outlet below the water line was a little better spew wise, but during "right" turns or when it got covered by water when running....the motor almost shut off. Like hitting the kill switch, Like my FX isn't a handful to ride anyway. Hence the "re-invention" of the rear exhaust. That's what I'm running now.
What do yo mean by "legal"?