McManus moved from Scotland to Australia while in primary school and while living in the Northern Territory played his junior rugby league in Katherine and later for the Palmerston Raiders in Darwin. He graduated to the Northern Territory Institute of Sport's rugby league programme and while playing for the Northern Territory in Darwin in the Australian under-18s championships in 2003 was signed by the Newcastle Knights.
Representative career
He was selected for Country in the City vs Country match on 8 May 2009.