I have already ordered the following:
1.Kenwood KFC-P709PS Performance Series 6-3/4" 80w RMS (240W max)for the front
2.Kenwood KFC-1693PS 61/2" 70w RMS (240W max)for the rear
3.Kenwood DPX503 head unit 22wX4 RMS
4.Kenwood KFC-XW800F 8" 600W 4-ohm Car Subwoofer 150w RMS.
What subwoofer RMS rating should I use for the sub and would I need another for the speakers. What do you recommend and what brand and power.

Thank You