How would you lose compression?
The same concept of freeing up power can be applied to the exhaust as well. To be more specific the gain or lack of will be different for every build and depends on what part is used. Again the context is kinda broad and we have to narrow the scope a bit for more accurate information. Generalizing whether a single part provides any performance or not just simply doesn't work. Some applications you see gains and others you don't. Even more than stock builds. I can elaborate if necessary. It boils down to air flow and restriction.