Nothing will ever beat our swedish subs http://en.wikipedia.org/wiki/Gotland_class_submarine
I dont know much about subs, but we had an instructor when i did my service that had been an sonar operator in the Gotland Class submarine, and he always said. if you have an silent enough engine no one will be able to catch you, not depending on what equipment they use to home in on you. The new submarines are so friggin good that they can clearly tell a small shipping vessel with maybe 2 engines and 3 props, to a bigger one with 2 engines and 5 prop blades. everything is about listening and analyzing the data.