I'm in the midst of relocating mine right now, the kits are pricey ($350 - $399) so I pieced together my own.

Check out PAKA Tools Cables on Amazon, great quality and reasonable prices; https://www.amazon.com/dp/B07V2K46VC?psc=1&ref=ppx_yo2ov_dt_b_product_details

This Caspers Electronics battery junction is perfect for under the hood; https://www.amazon.com/dp/B014T40XNQ?psc=1&ref=ppx_yo2ov_dt_b_product_details

And for mounting the battery, there are a bunch of options for the Optima models. I went with a more robust option in this milled aluminum mount; https://www.amazon.com/dp/B00S75H5S0?psc=1&ref=ppx_yo2ov_dt_b_product_details

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All in parts and hardware cost is about $220 for the DIY.