Hi! New member here!

I recently upgraded my '12 Boss suspension: Ford Racing springs, yellow Koni's, rear upper/lower control arms, relocation brackets and adjustable panhard bar.
The lower control arms are non-adjustable and are fitted with urethane bushings.
Everything fits well and seems to work as expected - no more wheel hop. ;-)
But now I have a whine from the rear end at freeway speeds under a load.
Was that noise there before and now I'm hearing it because the stiff bushings transfer the sound better?
Anyone else notice this after upgrading these components?

Looking forward to input and advise.
Thanks!
Dwain