@SOBO-87 said
I can’t speak specifically for the Viper but it’s very common IRL for HUDs horizontal FOV to exceed what is visible with both eyes through the HUD simultaneously. IE : you have to move your head to the side to see info at the edges of the HUD with both eyes.
Means that your seat position setting is not right. (Too far awar from harmonized position)
Don’t you have seat adjustment cues in your aircraft? ( Two white balls and one red ball or something similar)
See: https://aircrafttechnic.com/general_aviation/the-eye-reference-point/?amp=1