When mine was on Innova EVO Red Meat as well as their Chicken small bites kibbles, she was REALLY gassy too.
I've noticed little to no gas since her food's been changed for a few months to Petcurean's "now!" puppy formula
NOW! Grain Free Pet Food. I also mix in Orijen 6 Fish adult (couldn't find a puppy version). She mostly prefers the "now!" Turkey and Duck puppy (new formula became Turkey, Duck and Salmon for puppy) which are tiny bites but she chews/crunches through her food no matter the size anyway. She picks out the Orijen and drops them aside but eventually would get back to it when there's no other choice. I know it's not because the Orijen's a larger bite because in size it's smaller or same as the EVO red meat large bites she ate without complaint. If it's not the flavour then it must be that the sphere-like kibbles makes it tougher to break down the center. In either event, I'm just glad she's not constantly gassing in my lap, while she's walking, sleeping, anytime at any place!