Installing A Light Weight Battery
After 2.5 years my stock battery gave out, so I figured if it needs replacing might as well go with a lighter / high performance one. Many people use Optima batteries which are good for large sound systems, but actually heavier than the stock battery. Here's a comparison table of possible high-performance batteries and the stock one:
If you drive your car daily (battery recharges often) or only track and don't mind using a trickle charger for storage, you can get away with a very small battery for some significant weight savings. Since I drive my car mostly only on weekends and didn't want to bother with a trickle charger for storage, I went just one step lower capacity than stock (PC925LMJ). This is a very high performance battery with sealed cells (safer for racing), and excellent starting power (CCA), it saves you about 10 lb over stock (in the place where the Celica needs it most) and will still be able to power the alarm for ~3 weeks if the car is not used.
The dimensions are such that the "L" model with the reversed terminals fits nicely in the existing battery tray, when mounted on the side. Since this is a motorcycle battery, it does not come with SAE terminals out-of-the-box. The place I bought mine gave me a used pair for free. Use some thread-lock before screwing them on for set-and-forget operation.
The stock tie down is too big, and the tie down that came with my RMM strut bar is too tall. Summit Racing offers a billet aluminum tray + tie down if you want bling ($100), but I just used a cheap adjustable plastic one ($4) with the stock tie-hooks.
The tie-down is too wide for the small battery, so I pulled it apart, cut it, and hot-glued it back together. The tie end pieces fit nicely into the battery handles on one side, providing both side-to-side and front-back stability.
For about $40 more than a stock replacement battery you just shaved 10 lb of your car in a critical location - not as effective as battery relocation, but way easier / cheaper.