Honda GCV 160 cc OHV pressure washer muffler upgrade

Evening,

Owned this diamond pressure washer since new and it hasnt skipped a beat in the last 10 years but its about as loud as a 450 2 stroke banging off the rev limiter at WOT.

I've found some old forum posts that went nowhere about upgrading to the gcv160 generator muffler to quiet it down since it bolts right up.

Can anyone confirm if this is an option or a good part number to do this? The pressure washer is perfect for my needs but feel bad for the whole block when its running. Thanks