Question
 

Hi. I have a 800 Watt Pioneer Subwoofer. The Nominal (RMS) Output Power is 150 Watts and the Max (RMS) Output Power is 800 Watts. I was just wondering how much power i need like in a amp to power it?

Get an amp that can produce 250wrms into the load your sub has. Ignore the peak power ratings - they mean nothing. Pioneer makes pretty good stuff for being entry level and their subs can handle more than their rms rating. So if you get an amp that pushes 200-250wrms you'll be fine.

There's another thread going on here right now about overpower vs. underpowering.
http://www.canadiancaraudio.com/online/general-discussion/26738-effect-underpowering-overpowering.html

Read what Timmy Turtle has to say. I agree with over powering to give head-room.