Just make sure before putting these puppies in about your maximum allowable current for headlights.
For two headlights, you should be able to burn both filaments at the same time as for example when you flash.
You should be able to support (100+90)*2/12=32 Amps on the fusible link on the battery. If not, it's not safe to use these lights.
I use Koito H4s. As for HIDs, I'm not convinced of their price/performance ratio. But that's my opinion. And as far as intensity is concerned, it's written on the box that these bulbs are too bright (thus illegal) for road use.
HIDs, being for road use, might be actually less bright than these bulbs.