yes, mrfred..you gonna have to do the chop like everyone else here who has plastic windows
If you don't:
-overtime, it will leave a 1" or 2" rip in either mid corners or middle of the plastic windoe
-if the weather is cold and you didn't do the chop, it might crack the plastic
There's a lot of topic here regarding your concern. Search the thread "Plastic Window or Chop"
Here are some of them to keep you inform but not to scare you
*a new owner thread that didn't know about the chop*
http://986forum.com/forums/showthread.php?t=14196&highlight=Plastic+Windows
*what happen when it's cold but sunny outside thread*
http://986forum.com/forums/showthread.php?t=16540&highlight=Chop
*Plastic Window dilema*
http://986forum.com/forums/showthread.php?t=5039&highlight=Plastic+Windows