I did a test on my Footrocket today at the suggestion of another member. I rode it as per normal for a while until it was good and warmed up, then I took the hood off and rode with no hood on, thus having zero air restriction and it didn't make the tiniest difference in power on my 10mm 1017cc motor. I'm thinking if it were a race boat you should be worried, but for flatwater freestyle where you're just blipping the throttle mainly I don't believe it to be an issue.