George what is a "flow straightener'? Are you using the new digital controller?
The flow stabilizer is an add-on accessory for my age of Garn, I understand that they are now included in the new ones. It is installed in the final pass of the exhaust.....beyond the fan. It is suppose to increase efficiency slightly & help puffing. In my installation I can notice a more quiet and stable fan noise out the exhaust the without it.
I do not have the new controller.