you cant tell crap from quoting peak hp #s. Thats LESS than half the story. If the 350z was a little peaky on its hp I see this as nothing out of the ordinary. The Stock Z06 has a very broad area under the curve and great power from 3000 rpm all the way to 6800 or so.
The 350 could have any number of combos to reach 500+ rwhp and be ineffective.
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if it's cheap & reliable, it ain't fast, if it's fast & cheap, it ain't reliable, if it's fast & reliable, it ain't cheap