Definitely bigger than Adam's.

As Sarah's moans died down and became contented hums and sighs, she was able to hear something altogether unsurprising from the hallway in front of her door. The lewd noises she had made playing with her new endowments had attracted her cumsluts attention and led Adam to start masturbating while peeping on her. Bust still swelling, semi-hard dicks softly twitching with her heartbeat, Sarah got up and went to open her door.

There, Adam sat, two fingers knuckledeep in his snatch, the other hand busy with his expansive tit. He stared up at her through lustfilled eyes, mouth hanging slack and lusty moand rising from deep inside him. Adam's eyes went straight to her crotch, and what he saw filled him with a potent mix of glee and anticipation. His sister had two cocks now? Did this mean twice the jizz for him? Would he even be able to take them both? The thought made both his pussy and his butthole twitch.