Here's a YouTube video of 440 dyno tests, with/without unsilenced air cleaner.

Without: 380 hp at 5500 rpm.

With: 375 hp at 5500 rpm.

https://www.youtube.com/watch?v=yLdSsFfnDEg

Go to 26:58 - 30:33, about 3.5 minutes.

(Later in the video they get 400 hp by switching to Edelbrock aluminum intake manifold from original cast iron.)

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