Alex at ABR built me his 3.1 liter "Punisher " engine with forged rods and pistons, ported head with full Ferrea valvetrain. The engine is not louder than a factory N54. My Indy has the same car as I do and we've idled his factory engine next to mine. I've never had any false knock or any codes related to knock.
The choice of piston material and the piston to wall clearance is crucial to keeping noise down.
Alex did everything right and tight.
Good to see some feedback. Where are you at power and tuning wise?