hi
I don't think it's the speaker, one of the first thing I did to my iggy was to replace the Clarion head unit with A JVC miles better.
as for the speakers the Clarion's can take the stereo up to about 70 - 80% volume.
recently tried some sony X-plod 140watt max power, 30watts RMS power. but could only take the stero to about 50% before the bass started to distort every thing.
trust me change the head unit first
happy iggy sport owner.
