Ok, so from a female that has them.... ;)
I've had mine for 17yrs - second set and both over the muscle. I considered going under when I got my second set and because of my activities the Dr advised to keep them over. My mom, who is also and athlete and lifts, switched hers to under after 25yrs and hates them - when you flex it changes the shape of them and makes them look weird- she has also ruptured hers twice in the 6yrs they have been under.
If your girl is lean, like I am, you will see a little rippling when bending over when they are over, per my Dr the only cure is to gain weight.... I'll take the ripples, thanks!
The other question is silicone vs saline - i've had both and like the silicone way better - they stay softer. My mom is the same - she started with silicone, switched to saline and after 2 ruptures when back to silicone.
Another thought - you might both read a little about BII (Breast Implant Illness) I joined a FB group and my god! Implants make some women really sick - I, nor my mom have have had any issues so I'm sure it does not effect everyone but if you read what women say - they think its a matter of time for everyone but who really knows?? Good luck!

Call the plastic surgeon closest to muscle beach and ask what they think almost every woman there has fake tits and the surgeon closest to muscle beach probably has done hundreds of women that lift probably even for huge pro women that's what I would do

Well I can tell you I've dated a lot of strippers with breast implants. That being said, whether it's over the muscle or under the muscle they still look good, feel good, and taste great

That's all I got, sorry bro. LOL