10cm speakers will fit in the space no problem mate,but the will be to small to use the screw holes provided,so u mite hav to make sum kind of adaptor so that you have sumfin solid to screw the screws into,and u can put as powerful speakers as u want,the headunit wont be able to make the most of them though as it only supplies limited power,they would sound better run off an amp,so you should be fine with those speakers but ul have to make a little adaptor of sum sort