That's definitely an ecoboost. Check the tag holder on the front. That wide open bumper is a dead giveaway. More airflow allowed in to hit the intercooler.
Did you ever decide to buy these? If you go to the Putco website and search for 2021, they use the same part #: 95150 as what the previous year models use. Stage3 part # is 95150BPFD.
I have a 5.0 with almost 13k miles, same noise. I've just accepted it at this point. I installed a Borla ATAK several months ago and the only time I really hear it now is standing outside near the front of the truck or creeping through a drive-thru.
I just ordered the Borla ATAK 140867 from a site that had it listed at $1025 AND allowed me to use a 5% discount code to bring the price down to $974!!! Ordered it on Oct. 25th and received it on Oct. 28th