It all works surprisingly well for on-road use. On the streets and highways, the XDs motocross attributes allow you to use the visor to block the sun, while the large eye port and the motocross style chin bar offer enhanced peripheral vision. The street helmet-inspired face shield closes tightly to help keep wind noise, moisture and cold at bay. 
I wore the XD on a fully-faired FJR-1300 and on an un-faired V-Max and it remained calm, quiet and dry in all street riding scenarios, including a sudden downpour at 80mph on the freeway. Its highway refinement seems comparable to most normal street helmets, which is surprising, considering the big visor sticking out of its forehead.
The picture isn't so rosy, once you get on a Motocross or Supermoto track however, because the closed face shield doesn't allow enough airflow for heavy exertion. This caused me to ride with it in the cracked or fully-up position which is not ideal for safety. If you're looking for an off-road competition helmet, I'd recommend Arai's excellent VX series and a good set of goggles.
.jpg)
Arai Signet and Signet GT helmets have a loyal following among oval-headed riders, because the Signet has a longer - narrower interior, compared to most other helmets. This allows more forehead room and drastically cuts down on helmet pinch. For those of you with normal "round" heads, Arai offers the Quantum series, which has a more traditional fit, while still offering Arai's award winning safety, design and finish. The super popular RX-7/RR and awesome new RX-7/Corsair race helmets fall neatly between the Signet and Quantum and I find them to be very comfortable, once they are broken in.
The new Arai XD "Supermoto" helmet is closer to a Quantum than Signet shape, so if you have an oval head, or frequently suffer from forehead pinch, you might want to order a size larger than usual, or go with a different model of helmet. Unfortunately for me, I didnt notice the interior shape issue when I first put the XD on. However, my forehead started hurting 15 minutes into an hour and a half trip to Perris Kart Track, for a Yamaha Supermoto press ride. The day's schedule required that I press-on, but the forehead pinch became extremely unpleasant and tainted my experience with what otherwise seems to be a perfectly nice helmet.The 2004 Arai XD is Snell M2000 certified. It's available in five solid colors: Aluminum Grey, Aluminum Silver, Black, White, and Sport Blue, plus various patterns which have not yet been finalized. Exact pricing is also not yet determined, but it is expected to be in the $450 - $550 range, depending on graphics. The XD will be produced in six sizes from XS through XXL.
For more info on Arai and the 2003 line of Arai helmets, call Arai at their toll free number (800) 766-ARAI.