Bit of trimming, banging and hacking and I have one pipe the right size, shape (i think) and lined up with outlet. As it is now is near identical dimensions as 3 cylinder 1200cc Polaris jetski chamber. The belly is slightly fatter but I hope that doesn't matter too much? Can always squirt a bit of water in or smack a dent in it...
Seems more crisp with chambers. Reminds me of the CR500 I used to own....glorious....https://youtu.be/qJZtZ98PgmU