The answer to 'system upgrade making noise' is that a new HVAC system upgrade can sometimes make unusual noises due to a variety of potential issues. Common causes include improper installation, ductwork problems, or malfunctioning components. Symptoms may include rattling, banging, whistling, or other loud or irregular sounds coming from the system.
In many cases, these noises can be resolved through adjustments or minor repairs by a professional HVAC technician. However, in some situations, more significant issues may require more extensive work or even replacement of the new system. It's generally best to have a qualified HVAC expert inspect the system to diagnose the problem and recommend the appropriate solution.