I think I found something. This a Japanese company that's relatively new to the US. The springs might do exactly what I want. What do you guys think? They're listing for around $180 on RHD Japan. Not sure what else I'd have to pay going that route.
Part#: N134D
Compatibility:
2009+ 370Z
Chassis code: Z34
Specifications:
Approximate Drop:
Front -10mm to -15mm (-0.4inch to -0.6inch)
Rear -10mm to -15mm (-0.4inch to -0.6inch)
Spring Rates:
Front 8.15kg/mm
Rear 8.87kg/mm
Nissan 370Z Down Sus Springs 2009+ | RS-R USA