Excuse my ignorance, but what are ABRSM grade 8 and RCM gr.8 exams?
I don't recall taking any sort of exams, except when I tried for a scholarship at college (and learned only music majors are given them--although they were very nice and did praise my playing, so it wasn't a total bust).
ABRSM is the Associated Board of the Royal Schools of Music (based in the UK, but they have international exams in music, including where I live, in South Africa)
The RCM is the Royal Conservatory of Music in Toronto, Canada.
I don't know too much about the Canadian one but the ABRSM has grades in music, completely different to school grades. Grade 8 is about the same as first year university Bachelor of Music. In South Africa, you need about grade 7 to enter university studies in music.
The Canadian grades are a little different to the ABRSM.
Hope that helps a little