EPA did have noise regulations. A 455 with a shaker scoop at WOT is louder than a 350 with the same scoop at WOT. That's the only reasoning I can come up with. The design of the Formula hood may muffle some intake noise, making them quiet enough to pass noise regulations.
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1976 LeMans B09 Freeway Enforcer, 455/M40 Smokey
1977 Trans Am, 400/M21 Black/Gold Bandit. 44K actual miles
2017 Sierra SLT 1500 Z71 4X4 
2019 Canyon SLT Crew 4X4 
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