aftermarket stereos are always going to be better than stock.. but one thing that hardly anyone ever notices is MAX POWER AND CONSTANT POWER your radio thats 50W x 4 is NEVER going to be that high, basically if it gets struck by lightning it will give all 4 speakers 50 watts, your probably getting 17 - 22 watts of continuous power depending on the brand of stereo you have. always find out the RMS or Continuous power of a stereo to know how much power it is actually puting out, SAME THING WITH ALLL audio equipment, subs, speakers, amps, etc. but after market is pretty much always better than stock in most cases. and the factory will push out about as much as an aftermarket stereo but still not as good quality of sound.