Huh... I have yet to run my 10" 556xi suppressed, but it does have a setting specifically for rolling a suppressor. Never had any issues suppressing the 16" barrel in 551 (not patrol) gas piston length/config. I also have a new P556. Again no testing with a suppressor yet. I know there is a member here that used to offer a service for drilling additional suppressor ports in your gas valve. Not sure if he is still around? Additionally, JDi used to offer the 4 position valve for the 552/3 but they have been on backorder for as long as I can remember... https://www.shop.jdifirearms.com/4-Position-Gas-Valve-for-SG-552-3-SAN34554937.htmI am fully aware that 5.56 does not suppress well and these guns are not the best to run suppressed...