Yes, it is feasible to augment the insulation of an R6 ducting. This can be accomplished by encasing the ducting with an insulative material like fiberglass or foam board. Nevertheless, it is imperative to guarantee that the total insulation value of the system adheres to the prerequisite limits delineated by building codes and directives. It is also crucial to contemplate the potential effects on airflow and pressure reduction when affixing additional insulation to the ducting. Insulating the flex can lead to enhanced comfort and may result in financial savings through decreased energy consumption, albeit the savings might be marginal if the furnace fan is already operative.