I've read in Vida this:
* 2a-methyl: This substitution diminishes the androgenic activity and increases the anabolic of the steroid.
* 17a-methyl: increases oral availability, and usually, increases the Relative Binding Affinity with the androgenic receptors, increasing androgenic activity (but a 17a-methyl added to a 17b-hydroxy-5a-reduced compound does the opposite effect) and slightly diminishes aromatization.