The file
A Ferrari, a helicopter, a mustache and a guitar riff that sounds like Hawaii. The first season had a different, jazzier theme; the Post and Carpenter rocker arrived in season two and is the only one anyone remembers.
It was a Top 40 single in 1982. Tom Selleck's eyebrows in the freeze-frame are the other half of the memory.
Sources: Wikipedia — Magnum, P.I.