A product of the Brumbies academy, Faingaa's breakout season came in 2010 with the Queensland Reds. A former Australian captain at Under 19 level, where he led them to a World Championship, his Super Rugby bow with ACT was fast tracked in 2006 due to injuries. After establishing a place in the squad he played regularly for the Brumbies before moving to the Reds in 2009, along with twin brother Anthony. At the end of the 2010 Super 14 season, a year in which he had nailed down a starting berth at the Reds, he won a call-up to the full Australia squad.

His Test bow came against Fiji as a replacement but he started subsequent meetings with England and Ireland, although he and his front-row colleagues shipped two penalty tries to the English in Perth. Faingaa continued to be a regular presence in the side through the Tri-Nations and made history when named in the starting line-up along with his brother, against the All Blacks in Christchurch, when they becme the first set of twins since Mark and Glen Ella to start for the Wallabies in a Test.

Faingaa's remarkable rise continued in 2011 Super Rugby season. He was a key part of the side which tookt he Super Rugby title and his prolific form was further rewarded by Australia's coach Robbie Deans who named the hooker in his final 30-man squad for the 2011 World Cup, where he made two substitute appearances for the Wallabies.