Originally Posted by MR2NR

It will make a difference indeed if you replace the speakers. That said though, you can have the most powerful speakers in the world but you are still only putting the same amount of power into them. It is the starting point however though, the first of the building blocks. Upgrade the front speakers first, with sound deadener as well. Next you can upgrade the rear speakers. Third, you add a proper interface adaptor to allow you to expand the system easier and provide a rock solid output for your subwoofer. The subwoofer will notice an immediate difference. Next step is going to be to add an amplifier and deliver some power to those speakers. That will bring the system to life for you. Come up with a budget for things and I will come up with some great equipment for you.