HEH! HEH! HEH!
I have buried the speedo at 140mph many time without any buffeting.
I have hit 135 with full panniers and large bag on rear fender while on long trips a half dozen times as well without any buffeting issues.
This has been done with 3 shields and the giant fly.
I highly recommend the giant Fly. I have a bad neck, back,hip and knees.
I am a large (read wide) fellow and this fly protects me well enough I ride multi thousand mile trips regularly.
If you haven't lifted the front wheel, grabbed it from the front with both hands and checked up & down for slop in the steer head bearings, you should!