Malcolm,

Yes, the weston muffler has the inner 'genesis' pipes.

I'm running 16.5 x 12 and will try 17 x 12 or 17 x 13. The thing is that the I'm still at around 86+ with this set-up - each 3db represents a 100% increase or decrease in audio power. Noise seems to be predominantly low pitched muffler roar over which it's impossible to hear any prop tip noise. Short of either grossly overpropping the engine to peak at silly low revs or swapping out the muffler, I don't see where else a 4+dB drop is going to come from. The weston is iso mounted on the firewall, the DZ is on a Hyde ARI, prop is balanced and correct....what else?


Billy Bunter is running the DZ on same fuel, same prop, same mount (ok, it's a different airframe) with the Hatori set-up and getting in nicely under the limit - seems to make some sense for me to try that route.

Dave