After that first week of break-in Mark you'll remember mine were nearly silent. Just the slightest noise on deceleration if you focused on listening for it...barely audible.
Just a few months back SZ replaced my diff bushings (they were shot) and I was able to hear it slightly at 60-70 highway speeds with light throttle (gone if off). This is with SZ subframe spacers.
Still love them!
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