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The 71 455 is a mere 335 which puts it in the category of the garden variety high compression 400. Even a 69 350 HO is rated at 330 HP.
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But Steve, in '71 GM (and others) went to net HP and all HP ratings were quoted very conservatively in order to keep the Feds off their backs.
I JUST read - in a recent issue of one of the 2 Poncho mags - that the '71 455HO was the all-time most powerful Pontiac engine and many feel it is the most desirable.
Don't make me go looking for the article!!
Mac
(My signature, below, is email from an eBay scammer who tried to sell me a bogus Camaro from London with "free shipping." I sent him a fake Western union transfer receipt and complained to no end when he didn't ship the car! ) 
