Just a guess: some of these Euro power figures are given in Kw, which are about 25.4% lower than HP for the same power (134.1% higher each unit). If someone actually gave a figure in HP (but didn't say so), some helpful person might have "converted" it anyway.
If the 567 number is a conversion, the actual HP was 422.8 - a bit more likely?

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That would be pretty close to what the ET/speed relate to.

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Official Cookie and Mater Tormentor.

This is a race car, but it is street legal. Dynoed 527 rwhp, 10,7/121mph:

`66 Valiant

I can translate it if you want to

Calculated horsepower from http://www.dsm.org/tools/calchp.htm :
Simple Horsepower Calculations
Using the ET method, I come up with 484 horsepower
Using the Speed method, I come up with 415 horsepower
That 121mph (195kmh) is the top speed of the car. Engine just won`t rev any higher. They had the same trap speed with very bad start at time 12.5. They haven`t got found different gears for more speed (Toyota rear axle)