Hi Marshall, welcome to the forum.
Since you have a baro damper I assume (and you know what that gets you!
) you have the SWG. If so do you have a way to measure the draft? If not you can still adjust the power vent using a rheostat such as the one here:http://www.electricmotorwarehouse.com/kbwc.htm
Make sure you have the weight set correctly for the orientation (vertical mounting the weight should be on the right) also if it is mounted on a T or too close to a change in direction it will not be accurate. Set the weight to achieve a .04 draft and adjust the PV to keep the baro damper door from opening, should be just fluttering.
If you do not have a way to measure the draft you can PM me with your address to participate in the manometer loaner program. I highly recommend that you measure the draft and not rely on the weight position to set the rheostat on the PV.
The other thing that is important for quiet operation is maintenance on the PV, purchase some of the synthetic special oil for it from SWG and make sure you clean and lube the unit once every couple of months. They will growl at you if you don't.