The OGK fits better than the Shoei-RF800 that I had... OGK's also run about a size smaller. That is, I wear a Large Shoei but a Medium OGK. Maybe they have smaller heads in Japan?
Anyway, DexDirect has a sizeing guide on their website... just measure the circumference of your head at the eyebrows/temple... it was correct for me.
The OGK has a built in plastic breath guard that sometimes touches the front of my nose when I'm doing 120mph+... but never had the chin touch. The helmet is just as noisy as any other helmet... maybe even a little more with the design of the side plastic that holds the visor in place?
But, the rear wing actually works... little to no helmet lift at high speeds
The foam pads on the inside also snap in and out so you can take them out for washing.
The visor also has two little knobs, one on each far side for "tear-offs"... the helmet came with three smoked tear-offs and a pretty cool helmet bag that you can wear like a back pack. Not as cheesey as Shoei's bag.
Over all, a pretty trick helmet that no others have in my town.
M.