You know the 'no replacement for displacement' argument old-school muscle cars like the Hellcat represent? Here we put it to the test against two very much more high-tech heroes to see whether new-school tech like turbos and four-wheel drive can really can see off the shock and awe of 707hp of supercharged 6.2-litre V8. From Japan we have theNissan GT-R. And from Germany the Porsche 911 Turbo S. And quite a fight...