thanks for the link, it explanes the situation well, actually i should have goggled it before hik hik.
I'm not going for sub woofer and stuff, i just need a simple decent setup with decent quality sound, it doesnt need to be high volume. SO I have already pioneer 50x4 output setup in my car. But the speakers doesnt produce good quality sounds. They are sony 35W speakers. So thought to replace the speakers.
Sun lanka told that there are no 50W 6.5inch pioneer speakers, so i should have go for Hunma speakers. That made me confused and thought to ask from AL.