Your review: We needed to boost the air flow for a couple of rooms in our house when the A/C was on since we those rooms wouldn't cool properly. We tried those cheesy duct blowers that you can buy at home depot which did nothing. After adding these blowers (model VTX600L), WOW! Now those rooms are as cool as the coolest room in the house. They really work! They are also as quiet as can be expected--you only hear a slight rushing of air sound. I just purchased the KB Varispeed model K177-1002 blower motor controllers to control the blower speed. I asked the blower manufacturer for their recommendation and this is what they told me. I haven't installed these controllers yet, so I can't verify how well they work.