Here's the install in my Jeep. The amp on the bottom of the pic runs the sats, the amp at the top of the pic runs my 12w6. I am not powering anything with the h/u. The sound as a lot cleaner especially at higher volumes. and the headlights don't dim when the bass hits.



my h/u has a built in crossover with customizable frequency parameters.

 

The capacitor holds a charge so when your bass hits it takes the power from the capacitor and doesn't put a strain on the battery/alternator. For your 1000w amp a 1.0 or 1.5 farad capacitor would be fine.