I've browsed through the FAQ and found the following:
http://www.riocar.org/modules.php?op=modload&name=FAQ&file=index&myfaq=yes&id_cat=11&faqent=182#182

Note the following two options:
-volume_boost_FM=nnn
-disable_bassboost_FM=1

That's exactly what I was searching for!!! Praise the FAQ!
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---------------------------- MK1: 00314 (4GB) MK2a: 030103104 (30GB) Installed in a BMW 323ti