Blockcaver
WKR
they work marginal at best. Single digit decibeles decrease at most. Most effective at idle
I added a Kolpin Stealth Exhaust second muffler to my 2012 RZR 800 right after I bought it used in 2014. It quieted the machine down 7 dB at 3,000 RPM measured up around my ear while sitting in the driver''s seat. This allows me to talk to a passenger versus stock exhaust...yelling and never being heard without stopping. I installed the stock spark arrester into the exhaust discharge from the Kolpin Stealth muffler...fit perfectly. Best $140 add-on for my RZR by far and it is still working fine after 5 years. The dB was measured with the SPLnFFT app on my iPhone, which showed excellent correlation with a $2,000 sound meter we had where I worked. I did not notice any power decrease with the addition of the second muffler, however I am not a guy that rips, does jumps, doughnuts and drag races with it.
And 7 bB is a lot...the dB scale is logarithmic, not linear, meaning the perceived loudness to the ear was reduced hugely.
I would recommend trying one, or something similar to quiet down a loud machine. Good luck!