Flowmasters drone at certain RPMs. I had them on several of my cars but managed to tame it down by adding a layer of dampening material to the floors of the trunk which made it much more tolerable.

However, since the mufflers are so far back on a Lincoln I don’t know how much of a problem this would be.

The last Lincoln I messed with had old school glass pack mufflers on it about 18 inches long. It had a good sound but didn’t drone like Flowmasters do.