no base

Hello..i need help. Recently i bought a Honda crv 2007..audio system was really bad on the car so i changed the 4 specker on the car. Its kicker 300W MAX 100W RMS CSC65.. but its still sound really bad..little base, not clear sound..still have the original headunit..people Are saying head unit...

I am hoping someone here can help me out. Every time I turn up my radio, the base and volume will sound great for about 5 seconds. The volume starts to fade away as if someone is turning it down to less then half. It is very annoying and nobody has the solution. Ford claims that it is a factory...