I had one installed in my 27, 2 years ago. What I know for su The cockpit is a lot quieter without the noisy front vent (it is taped closed under the flapper). The performance of the side eyeball vent is greatly enhanced, and it blows a very nice stream of air towards my face when desired. So the cockpit is quieter and more comfortable. Most of our flights are flow fairly low in pretty humid air, so this is a big feature. The cone of silence behind you head makes sure that the air being exhausted comes from the cockpit, and not from the tail boom. It also doubles as a moose call if you land out and need to start living off the land while waiting for your retrieve crew. What I surmise: the performance gain is there, however my poor decision making would make it very hard for me actually put a number on it. It's not going to turn you into a wizard.