Our tunnel is not vented. I had not heard of it before. Interesting idea. To be honest the 60hp Evinrude ETEC pushes that 20 footer just fine the way it is. Even with a boat full of nets. We routinely carry 800 to 1000 pounds (including people) in our boat and it will get up on plane just fine. We are also not in that big of a hurry while we are working. Some times it is just nice to put around the lake.