You may not have liked the sound of your friend's recording, but chances are, your friend liked it, or it wouldn't have ended up like that--If your voice is similar to your friend's, you should find out how it was done, in order to avoid the same problem. Then read up on the various trick of the trade for enhancing a weak voice, and find a recording engineer who specializes in this--Often, the voice is recorded on more than one track--

If you don't have the same kind of voice, don't worry too much about your friend's problem--you will have a different set of things to deal with.