Interesting. I had the SS on mine with OEM 2014 GT500 manifolds, cat and mid pipe and the drone was horrible. I took them off and went to Ford Racing. Do you know if that is a 2.75" pipe?
Resonators do A LOT to knock down an otherwise rowdy exhaust note. I use them on just about everything I drive because the older i get, the more annoyed i am by droning or overly loud exhaust sound.