View Single Post
Old 09-30-2020, 07:05 PM   #6
slonomo
Searching for The Way
 
slonomo's Avatar
Yamaha
 
Join Date: Oct 2009
Location: Medina, Ohio (NEOHIO)
Posts: 11,421
Default Re: Predator 670cc muffler options

"Quiet" is very subjective. What one considers quiet is another's loud. What kind of decibels are you looking for?

A straight piped 670 will likely be in the 118 db range or higher. Zero back pressure.

Adding a stock atv muffler will get you down to 95 db. No significant added backpressure.

The Thermo King muffler is available in many brands, but they are nearly the same spec wise. The one I got is from Tractor Supply, made by Stanley I believe. It's considered a universal muffler.

Both the atv muffler and the Thermo King muffler will be quieter than the stock generator muffler that comes on the 670, which will probably be 105-109 db.

Going to a small muffler like a stock golf cart muffler will get you below 90 db, but will kill your power. Just measure the exhaust port on the 670 and measure the inlet and exhaust on a stock golf cart muffler.....big difference. All the extra power you're enjoying with the 670 will now be reduced by 30-40% from the added back pressure.

Any muffler you use will need to be adapted to fit your exhaust pipes.

You can buy a Decibel meter on Amazon for $20, that way you can put a number to your changes. Always test the decibels 20 inches behind the machine and 45 degrees to the side, and at 2500-3500 rpm.
slonomo is offline   Reply With Quote