Originally Posted by
SiZT
I'll concede that yours is noisy because of the gears, rotrex's (due to the way they are driven internally) aren't
The biggest 3 manufacturers, Procharger, Vortech and Paxton all use gears. Some helical cut, and some straight cut.
Rotrex would be a very small player in the market by comparison.
Likewise Powerdyne which uses a rubbish internal belt drive, although it would render it pretty quiet.