agree, not heavy... stock is heavier... check these out, the lightest are around 26 lbs in this size, and cost a lot more !
Wheels for 2009 Nissan 370Z Coupe Sport Package
there are some 19x10.5s that would be more like 23 lbs like the te37, but again 2-3x as much $ to save 2 lbs
18s are it, if you're going for weight !