We were on seperate tickets and in Y and still witnessed priority tagged luggage coming out late.
I don't believe there is priority immigration so be prepared for a long wait if it's busy.
Our next trip in a few months is on connecting tickets and I still wouldn't book a 2 hour connection again with the chaos that can occur at SGN arrivals.
Having said that, when it's not so busy it isn't uncommon to de-plane be through immigration and past the luggage scanners and outside within 20 minutes.