Unders give more of a natural look also very much depends on what profile your having high profile moderate or moderate plus, there is also Somthing called partial which means half and half under the muscle and over, I am having 275-300cc moderate plus under the muscle I’m 5’7 and weight 8 stone so quite slim I’m currently 34b I have no idea what size I’ll be after lol but I think I will go for 300cc