I'm being good at this today!! I disagree!!!
I've seen a couple of dyno results (see richards ducati ST FAQ and sigma performance site) that show putting holes in the airbox straightens out the power curve without needs any adjustments.
Every bike is different and it may not be true for all. The only real way you'll find out is to dyno it with and without the holes.
BTW adjusting mixture to compensate is just a turn of a potentiometer next to the ECU
[Edited on 13-7-2005 by moozaad]