Air injection pump on the 4.7L in 470 is located under the intake manifold. On the 4.6L in 460 it is in the front area by the power steering reservoir. That being said timing belt motors typically are quieter. Last vehicle I had with a timing belt was my wife's old '96 Mazda Protege she bought new.

Air injection pump only runs a few seconds at start up, so non issue. But you right, belt motors are typically a bit quieter than chain.

Air pump on mine seems to run 20-30 seconds or so. Perhaps algorithm on 470 was different. IIRC... even air pump operation on '14+ is different than 10-13. I thought there was a shutdown operation on '14+. I'll have to look at what the difference is.

More aggressive fan clutch when cold?

or just comes down to chain versus belt?

Recently bought a '13 460 with 67,000 miles on it and also have an '07 470 with 120,000 miles on it. Recently changed t belt and water pump on my 470; air injection pump has been disabled.

Love everything about my 460 and it is far more refined than my 470 but the engine/transmission combination in my 470 is just a peach. Hard to tell which is smoother, both are very quiet in the cabin after initial startup. Outside the car, 460 is louder on startup.

Big point here. The acoustics of a belt come at the cost of a longevity.