1) Blood Pressure,
2) Back Pumps,
3) Liver damage (even on a mild oral like Var
4) Lipids fucked,
5) and either test/mast or test/tren
...........are just five good reasons I can think of why that's a bad idea IMO.
You need to tell your bros to get some GH, tren or mast .... they have a small waist because they are still young (and an ectomorph probably) ... that shit will change as they grow everywhere. The core if for stability and it will eventually catch up proportionally to their rest of their physique IMO.