I was surprised about the limited gains through COBB. Stage 1 is only 20 & 20 and stage 2 and 2+ require bolt on mods (downpipes and fmic I believe) to get more. For $100 more than COBB, ESS will provide greater HP and TQ without needing any other mods. But, COBB does offer some cool user features.
'15 3500 HD Dually