What I meant was that low-end and mid-level Shimano non-drive side cups (the plastic ones) are flanged and don't thread in past where the flange meets the BB shell. When you space the BB toward the drive side using spacers, the plastic NDS cup needs to thread in further to provide adequate compression around the cartridge. The only way to do this is to file off the flanged section of the cup. Higher end BBs with metal NDS cups don't have that flange, and can be threaded in as far as they need to be. Sounds like the VO NDS cup is metal so it doesn't have this problem.