Yeah, its been posted before, perhaps even by me...
Hard manuvering aircraft leave wingtip contrails even in moderate humidity. Not jet contrails... Wingtip contrails.
The game already has the wingtip 'air show' smoke capability, this is just white smoke beyond a specified G-load.
Would add a ton to the game as far as realism, and yet it remains only a wishlist item...
Back me up, Homies!