What's better than a stock Nissan Skyline GT-R? Why, a Skyline GT-R chock full of high-performance bits fitted by the Japanese company's in-house tuner, Nismo, of course. Thus, the Nismo Skyline GT-R R-Tune was born. The engine, designated the R1, not only gained a new turbocharger and racing camshaft, but also received the hot-rod treatment, including a full balancing and polished ports, which allowed it to rev above 5,000 rpm and produce a full 443 HP. Other underhood…