It seems like there is new suspension kit out, Megan Racing Coilovers.
eBay Motors: 2009 Nissan 370Z Megan Racing Coilovers Damper Kit (item 300284031888 end time Jan-30-09 09:34:28 PST)
And in the descriptions, this suspension can also be used by G37 with spring rates of Spring Rates: 12kg Front and 8kg Rear.
One quick question, I would need to buy rear camber if I drop it more than 1 inch right?