Aftermarket Variable/Multi Speed Blower Kits
Try to find the installation papers for the furnace and check the installation specs. Most blower motors are 4 speed. As far as the noise is concerned, I just replaced my 20 year old furnace with a new Goodman unit and it is very loud compared to the old unit. With most of the newer units today, you can not just reduce the blower speed since it may cause the heat exchanger to over heat. I would call a Trane guy and ask for advice.