Phal outgrowing its pot

[ChauMayne]

I have a phal that has a large amount of roots (all in perfect health) and it is starting to outgrow its pot. The pot is already a large one and I really don't want to use anything larger.

This is one of my favorite plants and i don't want to hurt it, but it seems my only option is to remove some of the roots. What is the safest way to do this? And will it stunt the growth of my plant or slow its growth?

Thanks for your help.