2008 was a career-defining year for him, being switched between the forwards and the backs on the Tyrone side throughout most of the season. In the quarter final, while being one of a number of Tyrone players sporting a beard for the occasion, he scored a crucial goal against Dublin.
In October 2005, barely a month after his All-Ireland win, McMahon was part of the Omagh St Enda's team that reached the Tyrone Championship Final.
He was part of the Omagh CBSMacRory Cup team that shared the title in 2001 (the scheduled replay was abandoned, due to restrictions of crowd gatherings amid a Foot and Mouth outbreak), and reached the final in 2002.
His younger brother, Justin was the captain of the Tyrone Under 21s that won the 2006 Ulster Championship.
Notes: J Devine was on the starting lineup but had to withdraw from the squad due to a family bereavement. Stephen O'Neill's name was not in the match program due to there only being space for thirty names. He played, and came on as a substitute with the number 31 on his back.
Paul Quinn's name was not in the match program due to there only being space for thirty names.