Fresh Air intake Inconsistencies
 

Starting in 1973 the Trans Am hood scoops were closed. Yet, you could still get the ram air air cleaner on Formula's through 74'. Also, the 1974 GTO hood scoop was functional.
Why would Pontiac have fresh air intake on the GTO and Formula's but not on the Trans AM? I had read somewhere that it was due to some EPA noise rule. If that is true, how did the other's pass the rule?

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.