What amplifier power does the S-W8D2 need?

It is rated at 300 watts RMS, so pair it with an amp that delivers roughly that per channel at the final impedance. A more powerful amp works if gains are set conservatively.

How do I wire the dual 2-ohm voice coils?

Wire the coils in parallel for a 1-ohm final load or in series for 4 ohms. Check that your amplifier is stable at the impedance you choose.

Will it work in a sealed box?

Yes. Alpine rates it for sealed and ported enclosures. Sealed gives tighter, more controlled bass; ported plays louder in a larger box.

Is it shallow enough to fit behind a truck seat?

It is a shallow-mount design, which is its main advantage over standard-depth 8-inch subs. Measure your mounting depth and box space before buying.

Is an 8-inch sub enough bass?

It adds solid low-end fill to a factory system but won't match a 10- or 12-inch sub in depth or volume. It suits shoppers who value space over maximum output.