I have turned wrenches on diesels cummins being my prefference. I always argued against the water system, when looking for power. the water is great for consistent power band, but the cool air system and a rapid spool up turbo will greate even more hp. heat in the unit either type is a killer in power. while opperating temp of 180 to 200 is great for burn rate and clean burn is important, air to air will give the bigger bang for the buck.