I think you are getting confused here. The 80mins refers to how much audio you could store on the disc when burned as an audio CD (or I guess roughly how much in uncompressed wav files). If you want to burn the same music which you already have in compressed MP3 format (165MB) it will easily fit on the disc (about four times over in fact). The difference is whether you want to burn the info on the disc as compressed data (MP3) or .cda (CD audio format) which is uncompressed and thus larger in size.
The thing you have to consider is that if you burn it as compressed MP3, then you cannot play it directly on a standard CD player e.g. ghetto blaster or car stereo. (Some fancy CD players can play MP3 burned on a data disc directly but not many and you have to check about this.)
Hope this helps.