> Even without exotic engineering highly-boosted turbocharged 2.0L street-car I4s can put out upwards of 500 horsepower at 7-8000 RPM.
I'll call bullshit on that. After whatever you've done to a stock 4-cylinder motor to make it output 500 horsepower, you've got a racing engine, with all that entails. It's not properly a "street car" part anymore. :)