^^
That's a tough one.
No sounds, just a slight side to side motion thats noticeable in the seat and a little in the steering wheel, for the most part it was constant at those speeds. I never tried going any faster.
Every once in awhile when I changed lanes it would stop. I thought maybe it was just the road surface, but it's just too constant to be that.

I have checked the flex disc and they appear in good shape.