As a Sardaukar mercenary you are one of the highest trained soldiers anywhere. However, even Sardaukar know that every advantage counts. Therefore, House Corrino has provided special surgeons with experimental technologies. For a price, you can have some of these experimental surgeries performed, possibly increasing your muscle strength, giving you greater visual power, a more hardy life, and so on.
Once an enhancement has been performed, there is no way to reverse it.
There are five levels to every enhancement except visual, which has one.
See the surgical enhancement room in the main headquarters for more information.