Last month, we heard a rumor that, unlike with the previous Z06, Chevy is opting for natural aspiration with the new one. One Australian publication reported that the Z06 will make 617 hp from a naturally aspirated 5.5-liter V-8—believable, given the displacement, and similar to what Ferrari squeezed out of the 458's 4.5-liter mill. That would be less power than the old Z06, but with a sound like this and mid-engine handling, it's hard to imagine anyone complaining.
i recall an engine that produced 450HP naturally aspirated from the factory on a pushrod central camshaft platform- a BBC, as it was. it was a fire beathing monster.
ford offered up a 429 Boss, which was a hemispherical combustion chambered engine akin to a HEMI (but they couldn't call it that) that produced an unreal amount of ponies - exceeding 600HP (though it was rated lower in publication's for other reasons)... it was also NA.
both of them, at the peak range of their power, could run with anything today... the problem is getting into that band. sure, they produced exactly what they said they did and more, but not many people ever touched the RPM range they actually coughed that power up.
these flat plane engine have a massive range of power- instead of a range of perhaps 300-500RPM starting above 5k RPM, they start coughing it up off idle... so, that engine producing 450hp n/a in a flat plane, such as ferrari pioneered, have 'useful' power.
boost, be it nitro, turbo, or supercharger (or any of the variants) move the power band. they do more- such as cramming 12L of air/fuel into a possible 4L engine and making that engine, for all practical purposes, a 'displacement on demand' engine, but... in practice, though, the boost simply moves the powerband to a range that matches the engines/vehicles purpose. ... that means a flat plane engine in the C8 turning out 'only' 435HP will likely run circles around the similarly set up car that runs a push rod 45* engine... faster off the line, faster out of the corner, max power to the ground on the straights instead of a wind-up.
that said? that same engine boosted... uh-oh... that be something to fear as an opposing driver.
an aside- I had a diesel engine some years ago that put 617HP to teh ground along with 1187# of tq... and averaged 18MPG... clean as a whistle (i'm strongly opposed to 'rolling coal')... the powerband in that truck, because of compound turbos, was over 1500RPM range. I had power wherever i needed it and all of it was under 3k RPM. I miss that truck. it was 11k pounds dressed out, and could still run 0-60 in under 6 seconds... stripped down it could do it around 5 seconds... nobody would ever have guessed that- which is what made it fun.