i don't know much about the pg comps but their specs say they are rated at 60rms. the 6004 does 150rms per channel @ 4ohm. the 3004 would be a better choice i think for this application.This Cadence Txa6004 will be a nice amp to run the comps and sub. you can run the 3rd and 4th ch. bridged to the sub and ch. 1 and 2 to the comps.The amp is 25 inches in length so make sure you have room.
http://woofersetc.com/p6099/TXA6004--Cadence-4-Channel-High-Power-1200-Watt-Amplifier.htm