I remember when I was 17 I was forever tinkering with my bike to gain an extra mile an hour (Time well wasted I might add) out of it, I used to tinker and ride through the town, tinker and then ride through the town.
One day on a tinker run I was convinced what ever I had done had worked the bike felt faster and everything felt different, It was then i noticed I had forgotten my helmet
I can see the appeal of a full face helmet