Ok, I spoke with a tech at Antigravity Batteries yesterday, and he was very helpful. He confirmed that their larger batteries in the ATX series will work for daily driven car with 4-cylinder engines, even in cold climates. They are essentially motorcycle batteries, but the larger ones are rated for up to 2500cc engines, quite a bit bigger than our little 1600s. He said they are rated for -4 to 140 degrees F, and I'm assuming there's a bit of a margin of error/conservativism in that number, so -7F or -9F might still work. He recommended for cranks under 10F (above zero), to turn on the stereo for a couple minutes to warm the battery up before attempting the crank.
He recommended the heaviest duty one they have, the ATX30-HD. It's $500, but will net me over 20 pounds vs the stock battery and battery box. Weight reduction ain't cheep.
So yeah, I'm going forward with that in a couple months when I get the summer wheels/tires. I'm also holding off on the big brake kit until then. Between the shocks, subframe bracing, limited slip differential + slave cylinder, and carbon fiber hood swap, I have more than enough work scheduled for the next 3-5 weeks already.
The donuts were cheap, so I ordered both a steel wheel and an aluminum wheel to see which is lighter. About $110 each with shipping and tax.
So just tosummarize where I am so far in my weight reduction plan:
-Lighter wheels/tires: 30 lbs (Late April/Early May)
-Carbon fiber hood: 10 lbs (as soon as it comes in the mail)
-Replace full size spare with donut: 15 lbs (as soon as it comes in the mail)
-Big brake kit: 15 lbs (Late April/Early May)
-Lighter battery: 20 lbs (Late April/Early May)
Total estimated weight reduction: 90 lbs
And with my diet, I'm hoping to go from 190lbs to 180lbs, so 100 lbs total