We have a mod for them over here Loki customs does it . He opens them up and puts a whole in the baffle welds em back up . Works really well used it on 701 760 even xscream 865 . He spent some time developing it , something to do with back pressure you need some on a 2 stroke so he tried and tested different size hole measuring pressure blah blah other tech stuff I don't really understand .
There's ALOT of skis running them over here easily as good as most after Market boxes ( better in some cases ) in terms of performance but still heavier . Less than a 1/4 of the price though on a exchange basis ,as in give him your stocker you get a modded one . Hardly any louder than a stocker bit more of a deeper tone imo .