Tein made springs for our cars, but they were never widely available here. I checked into it a year or so ago. Supposedly they can be ordered through US Tein distributors.
http://www.tein.co.jp/stech2he.html
Here's the reply I recieved to my email to Tein.
Ken,
Hello and thank you for your interest in TEIN High Performance
Suspension. Unfortunately it seems that the SKH62-S1B00 had been
discontinued but the SKH62-M1B00 TEIN Japan has limited stock on this item
but it still can be special ordered. Please contact your local TEIN
Authorized Dealer for ordering information.
Best regards,
Sales
Staff @ TEIN USA INC.
9798 Firestone Blvd.
Downey, CA 90241
Phone: (562)861-9161
Fax: (562)861-9171