I just replaced the water pump on my 06 grand prix and now something is squealing like hell

according to this video, yes

https://video.search.yahoo.com/search/video?fr=mcafee&ei=UTF-8&p=2006+grand+prix+fuel+pump+replacement+video&type=E211US1494G0#id=1&vid=670a32828d489bc51569fe8c67013954&action=click

https://www.bing.com/search?q=2004+grand+prix+serpentine+belt+diagram&form=EDGNTC&qs=AS&cvid=738d3f0931444115b44f6f066f182f85&pq=2004%20grand%20prix%20ser

You can't 'fix' it but you can replace it.

https://www.youtube.com/watch?v=7CLO9IIAhCU

2006 Grand Prix Water Pump Replacement

I would lean more towards the water pump or the power steering pump. Check the fluid in your power steering reservoir and watch the temp gauge for hotter than normal.

To get that last bolt out you need to move the power steering pump out of the way. Just remove the two bolts holding the PS pump and push it aside. You don't have to remove the pump hoses you just need to move it an inch towards the firewall.

have a pressure test done so that you can see where it is leaking from.. If it is in the side of the block it may be a rusted welsh plug. Check inside the car for a leaking heater core and hoses . Check the drain hole under the water pump as it may be leaking from that hole while the pump is running ( water pump seal)

no it doesn't

check the oil to see if the is water in it it will look grayish and bubbley if there is water in oil you may have a cracked head

You have got something out of whack there, take a straight edge, like a metal ruler or framing square and line up the pulleys, try to find one that is out of whack. Wiggle the crank pulley and see if it is loose. If the belt is off, wiggle all the pulleys to see if one is loose. One of the pumps, comp, alt, etc, is either bent or has a broken bracket. Is the tensioner tight? Too tight? It should be ok if nothing squeals. Hope this helps.

first take the 4 bolts that hold the water pump pulley out, do this while the belt still on, it's easier because the pulley won't turn on you.
remove the pulley then take the 8 bolts around the water pump then pry the pump out.