I have found these items to all but eliminate buffeting on my 2017 FLHXS M8:

Harley Fork deflectors Part# 57400143 / $100
Kuryakyn Triple tree deflector Amazon 1404 Chr -1405 Blk / $30
Faring adj wing deflectors - Amazon $26 (2014-17)
Recurve windscreen your choice-your height dependent $100+
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