Saw the Bear Eradispeed mention on Tirerack, which led to Baer's website, where they quite gracefully admit they don't make the parts, Disc Brakes Australia does.
Check the DBA website out. Interesting line of brake rotors and etc. There is a listing for the G50, but unfortunately it only shows a direct replacement, not the trick two piece.
http://www.dba.com.au/
Any of our members down under know about this outfit? Quite an extensive line, including some Infinitis sold, plus maybe we could rely on interchangability with other Nissan lines.
