Good thing you are changing the plugs, too. If it has been several thousand miles since the last change (dang platinum plugs), the plug wires aren't the only things that will give you grief trying to remove, as the plugs may be molecularly bonded to the head! Use some anti-seize compound when you reinstall.

__________________
2009 ML350 (106K) - Family vehicle
2001 CLK430 Cabriolet (80K) - Wife's car
2005 BMW 645CI (138K) - My daily driver
2016 Mustang (32K) - Daughter's car