Originally Posted by bigaudiofanat

A 8 inch sub will give you a more fuller sound than not having one. In a z an 8 will give you solid bass but not put out anything loud or rattle anything.

200 watts is not needed but can be used for a 8 inch.

I recommend looking at a polk mm sub. Or take a look at the JL if you want to go with another brand that makes good subs in this size. Just make sure to turn the gain down for either and tune it for no distortion.

8W3V3-4 - JL Audio 8" 150 Watt RMS 4 Ohm Subwoofer
MM840D - Polk Audio Mobile Monitor Series 8" sub with dual 4-ohm voice coils

For an amp take a look at these.

MRP-M500 - Alpine Mono 500W subwoofer amplifier

P400-1 - Rockford Fosgate 400 Watt Monoblock Punch Series Amplifier

PA400.1 - Polk Audio 1 Ch 400 Watt Amplifier