As said above, I think weight reduction is best option, without voiding warranty.
Anyone go with a CF driveshaft?

These cars are HEAVY, seats, battery, driveshaft, maybe drop 150lbs, but would probably cost $2k

Edit: Did a little searching and I wouldn't bother with a DS, looks like $1500-$2000 for only 10 or 15lbs savings.
Surprisingly hard to find the weights on these.