Installing in car entertainment..any pointers?

Use good routing, grounding, shielding, filtering practices, avoid ground loops, and lastly don't void your car's warranty.

I don't know where you plan to get your power. If you're running straight to the battery or any point under the hood then be careful to route your wires away from sources of electrical noise like the orange power wires or power converter.

The 12 V comes from the power converter, so you might need additional filtering. I think you said you planned on using a super capacitor. You could also consider an inline filter.

Use shielded audio cables. You might need a low pass inline filter between the source and amp, but let's hope not.

Run a separate ground wire for your amp. Don't just chassis ground it. Figure out where your source is grounded and ground there.

Do a good job. Fuse any circuits you run off the battery. Make secure connections. Insulate and protect from abrasion. An electrical fire won't be covered by your warranty.