okay, I figured out what's on that homepage:
http://www.tigerdude.com/japan/license/veh.html


cars over 2000cc have a 3xx number, and from 660cc - 2000cc a 5xx number.

But I always see FD's with 3xx numbers, so I guess it's different for rotary cars.
I saw FC's too with a 3xx number,...but only s5's.
Do s4 FC's have a 5xx number? I only found one S4 without censored licenseplates on the internet, and it was hard to read.
So do S4 FC's have a 5xx number?

I'm asking because I want to figure out all about japanese license plates, and I want to buy japanese license plates for photoshootings, euro license plates are ugly !
But anyway....is there maybe a 5xx plate HP limit for rotary cars? maybe 200hp? The S2000 has 1997cc but a 3xx number too

 

I'ts more complicated than that. Number plates have changed with years and old ones have only two number on the upper side. The second number (new ones) indicates if the plate is a randmly choosed by the authorities or a special ordered one. The number you'r talking about is related to the category.

Anyway, if you want japanese plates only for shootings what difference would it make?

And remember, Japanese plates cannot be sold or exported from Japan. There are some cars illegally exported with license plates that are then sold on Ebay for instance... Just remember this is illegal.

I've also seem many "strange" numbers within plates for sale on the internet, numbers usually used by japanese gansters... I don't think it's really "cool" anyway and I'd suggest you not to waste money on that but this is not my call...

 

The number 300 at the top refers to the cars category for taxing and shakken costs and relates to how thirsty the cars is and the size.

You can buy fakes from the net, i have seen them somewhere but cant remember where. I reckon they look great on a car!