ISO 9001 vs Six Sigma Quality Programs

I know this is not the correct forum,but I was wondering what you thought of Quality Improvement programs like ISO , Six Sigma , etc. We are a ISO 9001 company and I was thinking
about the Six Sigma program. I am looking for a less costly program , and something that will help us with a more internal disciplined approach to quality improvement .

Thanks in advance,

BP are ISO 9001.

Quality improvement is essential but I have serious doubts about the actual usefulness of the different standards.

'ISO 9001 doesn't stop catastrophes, but they are some of the best documented catastrophes you will ever see (until you hear the whirring of shredder motors).'

Bryan