Strange but good. Have a tech come out and measure the static supply side vs. return. It the return is restrictive, add more filtration or ducting according to need. If high on supply side then add ducting refinements to lower it a bit.
Once you have it perfected or even if you leave it as is, you still have room to adjust dampers to balance the airflow. Airflow adjustment will increase the static and could create noise issues if the static is to high.
You may have enough room to balance the airflow without changes so you will need a good tech that has experience with this. I assume you have a 4" filter but if not I'd add it regardless.