The FA20 2.0L engine is near 200hp and squeezing more power is difficult without the addition of a turbo or supercharger. I'm a big fan of reducing weight as a means of improving the performance of your 86. When horsepower isn’t on your side, play to your advantages by cutting excess weight in an already lightweight car. The standard Panasonic battery is horribly heavy at 30lbs! It's probably the largest battery I've ever seen come in a sport compact car such as the FRZ. Swapping this battery with a lightweight unit from Braille will reduce around 20lbs from the frontend of your BRZ. This will improve acceleration feel and braking. The biggest concern most people have is how to install a smaller battery without having to reroute wires, fabricate a holder, or spend a lot of money on a custom tie down. Using our pics below, you can install a Braille B14115 into your 86 for around $200. Comparable kits cost upwards of $300+
Pack of Home Depot Poly washers
You will use your factory J-hooks to mount the battery and washers to accommodate for the shorter battery. Simply adjust the Braille FRP tie down and tighten everything down. If you did everything right, the battery should not move at all. And how has this smaller battery performed? I've seen no loss in usability and start-up of our BRZ. If you daily your 86, you should be giving it enough juice so that you don't have to babysit it on a charger. I've left the car sitting for a little over a week and it still fires right up. If you drive it less than that, I recommend putting it on a battery tender. This battery also is within most motorsport rules and STX in autocross.