The weight of that Saito 82 would be great on the Seawind. Not too sure about a decent amount of performance though like a 91FX or Saito 100, particularly if you add a pound of retracts.

In regards to the 90 degree manifold extension for the saito, I am currently using one on a brand new Saito 82 in a .40size YAK. You are right, it routes the muffler just about 180 degrees opposite direction from the crankshaft. Very nice to keep the muffler totally in the cowling on the YAK!