Interesting point. Where are the obvious weight saves on the 350Z?
Weight reduction table
Item Weight drop Approx. cost (USD)
Ti exhaust 50 lbs $1200
Carbon fiber hatch 45 lbs
Racing seats 15 lbs
Remove hatch weight 1.64 lbs
Remove rear wiper 5 lbs
Lightweight wheels 45 lbs
Remove rear speakers 5 lbs
Remove sub bracket 2.5 lbs
Remove spare and accessories 50 lbs
Lightweight flywheel 20 lbs
Light pulleys 5 lbs
Strut bar 10 lbs
Less gas 90 lbs
Wiper fluid 10 lbs
Battery (odyssey PC680) 20 lbs $150
from: http://www.350z-tech.com/zwiki/Weight_Reduction_Guide
funny enough, the most effective weight reduction measure is driving your car with an empty fuel tank