@edrick i don't have a way to grind it but maxing flight gives a flat bonus which is a rather nice +3 i think
For people talking about how Billy looks i entirely agree, and as to needing to re-render the whole game for a body change that is not entirely true, the well endowed perk is only more work for when Billy is naked and the penis is showing, for a good number of the sex scenes you can't tell which prop is being used due to the penis being inside the girl and as such i doubt Baal changes it, why make more work for yourself and increase the game data size?
While a body change for say herculean strength or polymorphism would be a huge work load should the changes be subtle or restricted to the body rather than the face like in the dream sequence as mentioned by
@tx650 i think the work load would not be undo-able and this is why:
-If Baal is any good he's saving scenes in Daz all the time and should have a near or ready to render version of pretty much every scene meaning setup time would be restricted to re-posing and the like, most of the work would be done.
-even in sex-centric image sets like obsessive not all of them actually show billy and if they do it is often a head shot, an example being in the nympho image set for Sam as of v17 the set contains 50 images, 11 of these don't show billy at all and a further 5 only show Billy clothed and from the shoulder up, the former of these would not need to be rendered again and the later depends on how pronounced the body change is.
-Quite a few renders have an alpha channel as the background so they overlay on the applicable background, these take significantly less time to render than complete scenes.
I'd say that the number of scenes that would need to be reproduced should Billy have a significant body change is around 1/2 to 3/4 depending on how drastic the change is, if the change would not show through full school uniform for example then the work load would obviously be lower.
I'm not suggesting that this will happen or even that it's likely to happen just that it is possible and not necessarily as much work as it sounds, I wouldn't hold your breathe though unless Baal hires a dedicated render monkey.