Hello
Currently, AOS servers prevent you from connect if some of the kv6 models you use are not of default size - a cube of 6x6x6 for the head for example - to prevent abuse such as making big arrows over a player's head, making him much easier to spot.
My suggestion is to give a little tolerance to that, allow for example 6x6x6 to 8x8x8 heads. Size would not significantly increase how you can see other players, but a few more voxels than current size would allow nicer modding for the head, if you want to make some hats or helmets, such as a german spiked helmet or a tricorn hat, instead of having to deal with player head's original size.
Of course, current head models are still within allowed size and will work without any modification needed
+ Improved modding
+ Still prevent reskinning abuse
+ No effect on current skins
- Maybe one more reason that rage players will use...
[EDIT] although it allows changing the size of the model, it does not change the hitbox. Just as a shot in the hat makes no injury. Using a bigger model will not give you easier headshots