Can't believe no one has mentioned these three laps. Freddie Frith's first 90mph lap in 1937 before the Mountain was widened for 1938, on a rigid Norton.
Ray Amm's 97mph lap in 1953. 97 would still be quick today on a naked long stroke Manx.
Got to mention my nephew's first sub 18 minute lap in 2002, which still blows my mind thinking about it.
And after those Bob Mac was always my absolute hero, so how about in 1961, 99.58mph on a 250 which broke John Surtees 350 lap record.