I got a WAYS to go, but here's the WIP so far... FINALLY knowing the secrets (at least one) on doing textures, the world feels like my oyster. I'm fixing up the obvious trouble spots, making her patterns a bit more 4k, hopefully. She'll be a Clydesdale, so most of the issues on her hands and feet will be covered by fur. Well, what do you think so far? https://ibb.co/h9kNJKP https://ibb.co/YkkmpCH https://ibb.co/Wtt28qw https://ibb.co/YkVLGCW
P.S.: I noticed that I may have gotten carried away in the forums. Sorry, got excited and was trying to help! I got the answers I'm content with, so I'll just focus on this post on updating this model.
He's using m_muscular, I'm pretty sure, since this character was made before we had f_athletic available. I think. Can't remember the exact date and version it became available.
The trick to it is to only slide the BodyTypeInfluence slider in the CharacterBuilder menu part of the way to the maximum. At around 0.5 - 0.6 you've got plenty of muscle definition without completely losing the base mesh's feminine shape. If you're looking for softer muscle definition for a more traditionally feminine look, go even lower with the slider. The rest is a matter of tweaking the BoneOptions until you're satisfied with the shape.
Here's a quick and dirty example of how the numbers might look. Note that especially SpineScale's X axis needs to be squashed very near to the 0.5 minimum limit to get that all-important hourglass figure when the BodyTypeInfluence is relatively high. It's also generally a good idea to pinch in the shoulders with UpperChestScale and Arms Spacing, as shoulders significantly broader than the hips creates a distinctly masculine silhouette, which is probably what you're specifically trying to avoid here.
I think @Dogson said some time ago he's been working on a f_muscular body type, too, so maybe we'll have that option to work with soon-ish. If not, the next release's custom mesh offset system should allow us users far greater control of the body types' shapes, which will be very helpful as well.
Ah, I think you mean the bra physics sliders. They're a bit hidden away these days, but they're still there. In posing mode, in the outliner menus, you've got PoseClothingOverride. You need to check both the Override box and UseBraPhysics box that appears when Override is checked. Then you should see the sliders and they'll affect the tits.
Here's a couple of screenshots to help you locate it: