if i play 4.3 in the 16 9 my sens its higest or lower?

 

For me, it depends on the game. Games of which VFOV is fixed can not affect my feelings of sensitivity(like COD6, battlefield series, CSGO no stretch), but if the HFOV is fixed, I will adjust my sensitivity depending on the actuall VFOV of the game(like cs1.6, A.V.A), and i may use 4:3 to get a bigger VFOV for this kind of game is usually old and designed for 4:3.