I'd love to know this as well. I've heard that the factory system is pretty efficient, so I'm curious on how much can be achieved without making big changes to the system. I think the main Intake+Tune gains are from changes in the tune rather than the other intakes too. Steeda's intake listing for the no-tune doesn't have horsepower/torque gains but the 15-17 gt ones do, so maybe they haven't dyno tested yet.
the no-tune requires usually yields about 10-15whp gains, it's the same as the tune required, the only difference is PMAS includes the MAF sensor that is calibrated to work with the stock tune.