After some searching on Ebay and the 400GreybBike forum, I was contacted by someone who had a full Yamamoto race exhaust to sell for $300. Given that new systems are over $1000 this represented a good deal, so we bought it.
However, on inspection it appeared the internal baffle (the perforated tube that goes inside the muffler) was damaged and would probably impede the flow of gas, not such a good deal then.
No matter, we can rebuilt it, we have the technology (the technology in this case being an angle grinder). Our plan was to use the old exhaust as a donor, hack it open and re-use the baffle. So that’s just what we did.
Most mufflers can be taken apart so you can replace the sound-proof glass-fibre inside them as it breaks down over the years and loses its effectiveness.
Basically, you drill out the rivets at one end (or both ends) and pull off the end caps, easy(ish).
We did the same with the donor can and set about fitting its baffle to the new can. Took a bit fiddling but we got it in then packed it with new glass-fibre (dont get this shit on your hands btw, it’s really itchy and a bugger to get off).
Fitting was quite easy, the Yamamoto exhaust is a well made system and goes together without dramas. Probably the trickiest part about fitting any exhaust system to an NC30 is getting to the rear manifold, a socket set with a universal joint is useful.The radiator doesn’t have to be removed to get to the front manifolds but you need to loosen it and pull it forward a bit.
It certainly looks better that the other piece of junk, and when we fired it up it sounded good.