Yes and No. Amp recommends that size but that particular version only has 1 terminal. Weird to have 1 terminal for 250-300A grade power wire but then directly advertise that the amp has an internal 450A fuse ? (I guess skar figures if your buying a budget amp your never going to spend 2000+ dollars on electrical upgrades)
DC, Singer, and Mechman are the brands you should be eyeballing. This is an example of one DC makes for your particular car
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In regards to size depends on what you actually want to accomplish, what the companies actually make for your vechicle, and what can you realistically afford. Most of these aftermarket alts are anywhere from like 200A to 370A range.
I would start with aftermarket alt, a really good XS battery under the hood, and big 3. From that point you can monitor usage/voltage and see if more batteries are even needed