Parameter estimation is possibly the most important step in mechanism generation, especially for flux-based algorithms like the one used in RMG. Because the criteria for selecting species to add into the model depends on the calculated reaction flux to those species, thermochemistry and rate constant predictions must not only be accurate for important species, but they must be reasonably correct for unimportant species, so that they can be properly neglected. The estimation algorithms rely on data which have been collected and stored in the RMG-database. This release of RMG includes both newly added data and new estimation algorithms.