I have one in the Winchester M70 Classic Stainless. It's a great feature - accuracy can become superb and recoil is reduced, but, like a muzzle brake, it can be loud.
If your friend can't stand the added muzzle blast, then there used to be available (if there still is) a "BOSS" system without the holes. In this manner, you can still tune your loads without the added muzzle blast.
Zachary