Surfing the interwebs this morning and stumbled upon Steeda's (new?) S550 x-pipe. Heck of a resonator delete, especially being half the price of the Ford Performance x-pipe.
https://www.steeda.com/Steeda-S550-Mustang-GT-50L-Coyote-304SS-Resonator-Delete-X-Pipe-2015-2018_p_15368.html
I called...
Love these forums. Just discovered this problem on my new 17... First noticed it at 300 miles in, didn't think much of it, figured it just flung some excess from an over greased part. At 1800 miles now, and just wiped off a gobs of the stuff. Schedule service for next week!
Shiftpoint,
When did you switch over to the Steeda setup? I got rid of the stock thing about 300 miles in!
One of those things where I probably didn't give it any though being stock, but changing the piece made me extremely cognizant of any weird feelings.
Thanks for the update rj! I've had my car for about a week, and began noticing the vibration after letting her breathe in the higher rpms a couple of times. Good to know that it should settle down after a while.