Mmmm dunno about that 400hp limit thing due to air cooling. There were plenty of modified 964 and 993 turbo 3.6's out there making 600+ rwhp. Eddie Bello's famous 964 made somewhere around 1200 rwhp. The biggest reason Porsche made the move to water cooling is cost - they're in the business to make lots of money, not to be nostalgic or appeal to gear heads. There *are* some benefits to the new design, ther air cooled head design really didn't allow for effective implementation of 4v/cylinder (yes even the 993's are only 2 valves per cylinder). Additionally, while lack of a water cooling system eliminates any problems associated with well.... water. But engineering of these motors, especially from a metallurgical point of view, is compicated...which makes them expensive to make and repair. 993's and before - are Porsche Porsches. 996 and after are Porsche BMW's. Excellent cars, but not really any heritage left from the original 911 other than a flat 6 engine in the back and the badge on the hood. And that's why people pay more for 993's, because they're the last of the 'heritage'. Air cooled 911's have a very unique feel, some love them, some don't. Take a look at the market for early 911's these days, it's crazy (wish I would have kept mine!).