In the early 1990s, Pablo Spiller worked on North & Williamson's application of the New Institutional Economics, on the conditions of credible network reforms. Credibility is defined as the capacity to provide reform commitments. This work, started from a Positive Political Economics Veto Point Model, has been constructed and applied with good results. The Author will show the consequences of the 'credibility as a trade off' concept in the efficiency of Regulatory Instruments studied and then introduce two improvements. Self-Regulation is introduced and their performance reconsidered in order to achieve the trade off between commitment and flexibility.