Porsche have been hitting the headlines lately with all manner of new models and technology. From the upcoming Macan SUV to the Panamera S E-Hybrid and 911 GT3 RS, the German sports car maker seems to be extending its market reach in all the right places. This got us thinking, however, about the Porsche’s that have gone before and the growing popularity of the older, ‘purer’, 911s. A watershed in the 911s history is that of the move from an air- to water-cooled flat-six. This video takes a look at both, evaluating the pros and cons when it comes to the driving experience.