I'm looking at some fake HID bulbs and there are different types like H1, H3, H4, etc. Whats the difference between all these? Is there a best one?

 

The H1, H2, H3... is just the type of the bulbs. My impreza'99 2.5RS is using H4! I think you should get the H4 too.

 

They all suck! Don't get them. The HID "look" bulbs are extremely hard to see with. I had a set on my bike and even riding around with my highs on didn't help the fact that I couldn't see crap. So I put one stock bulb back in to the high beam (has 2 high bulbs). Went out to a dark spot of road and flipped on the highs. You could clearly see the light from the stock bulb hitting the ground, but the "HID" bulbs light was no where to be seen. So bad that I even put my hand infront of the light to verify it was still on. They may look brighter, but they arn't. Looking cool doesn't do you much good when you run off the road because your field of vision is only 10 feet at night. I only wish I had a camera handy to show you the pics of how much they really suck. The spectrum of light emitted by them is actually harder for the human eye to see, and much worse for your night vision.

So in closing.....don't get them....just a ricer mod.