Caruso, you might have another option if you like wrenching around and fiddling and tweaking etc. ...
You could use the muffler with the compensation tube pointing up, fit a long(er) pipe to it, and an adjustable piston, so that the length of this new pipe is variable.
Then run the bike at different revs and see how she sounds and performs.
This kind of contraption is a 'tunable resonance pipe', and helps to have low down grunt vs. high end screaming ??? horsepower.
BTW Porsche did something along these lines for the earlier road-legal 911Turbos (the ones with the older, 4-on-the-floor) they had a ballasted trap door in the muffler so that when boost exceeded a certain limit, the exhaust would not be baffled but 'straight through'
Lovely screamer from a flat 6
As they say in Kentucky, it's horses for courses.
Maurizio
PS OK OK stop horsing around, flog the muffs on eBay and get the other kind