Check out this thread.
http://aquariacanada.com/forums/show...&threadid=7365
I had done that mod back when I had a prizm skimmer. The added 3 or so inches by the plumb quik adapter made a big difference, I could open the flow valve the whole way getting more flow in the tank and more more water throught the skimmer.
If you don't want to register on that forum, pm me your email address and I can email you the pictures.