This one is a Rocket Dancer made by TFS Motorsports... the company went out of business in Japanland in 96 and this spoiler was discontinued in 94 (since the s13 was no longer made).

Wangan still makes a spoiler like that, but the Wangan one is MUCH bigger (that's why I hopped on this one.. it's small enough that I didn't need an aero kit to balance out the rest of the car lol).

They're generally referred to as whaletails.