Replaced old lead acid battery (37 ½ pounds) with a Voltphreaks VPH750 lithium ion battery and NCI bracket (5 ¼ pounds), saving 32 ¼ pounds!
The VPH750 battery has an automatic low voltage cutoff which can turn the battery off when it gets low, so it won't die completely and can just be turned back on to start the car. It also has a power button so I can just turn it off during the winter instead of having to trickle charge it.
Re-installed Reverie XC carbon fiber seat after getting a seat pad for it to raise me up back to the level of the original seat. Now my elbows don't hit the (much higher) sides of the seat when turning and my field of vision is better. I still need to find a different seat belt buckle that has webbing behind it so I can bolt it into the seat in place of the original buckle and pass it through the lap belt hole in the seat.
Also had the car waxed.