The one that I cut open was a completely dry chamber stock. I can't remember if I cut open a 750 pipe or a 650 pipe, but I would be surprised if they are not both dry chambers as the two systems are very similiar. The water from the water jacketed section comes out around the outside of the pipe under the rubber boot into the waterbox. I have an extra line out of my head to bypass some of the water out of the waterbox, but it's not the same as the "dry pipe" modification people do to the 650sx pipe which has a ton of water running through the chamber in stock configuration.