factory mariner pipe made by factory but with the mariner logo on it also since mariner was the one selling those in their product line. they had the factory/mariner 550 half pipe and 750 limited pipe too. since that one has the one piece chamber, its the newer model and thats also why it has the 3 head pipe screws. the old first gen A pipes were 2 piece chamber and 2 head pipe screws. the ports were smaller on the gen 1 head pipes too. the smaller ports matched up with the 1986 thru 1990 non diverted exhaust manifolds and the new style with 3 screws and bigger ports matched up with the 1991 thru 1995 650 with the diverted manifold that had a larger exit port. yours/kawi head pipe uses the longer 3 bolts to bolt it to the manifold, since that flange is thicker than the yami B head pipe. i've used the kawi ones on my superjets and actually like the thicker kawi ones better since they are less prone to cracking at the flange. i've seen yami B pipes for sale on the X with a hairline crack in the pic. cracked = junk unless its pro welded.