When my new Trane XT80 was installed, because of the size of the new coil, they had to convert to side-return (my old furnace sat on a box and return air flowed up from the bottom)
The return from upstairs now comes in on the left side of the furnace (filter on that side), the basement return (16'x16") now comes in on the right (there's about 17" from the wall to the furnace)
Here in the basement the new furnace is much noisier than the old.
Right now the basement return has the filter on the wall - I'm going to have them add another holder inside the furnace so I can move the filter there (instead of on the wall)
Any other tips on reducing noise?