I recently bought 4 Pioneer TS-G670M for my '99 Nissan Altima. The installation went fine and everything but there seems to be quality issues when playing music at high volumes. Well, as of now I am using the stock head unit that came with the car because of money problems. But anyways, my problem is whenever I turn the volume up and there is bass it seems the speakers stop working for a split second then when there is another bass part it does it again. I was thinking that the current head unit can't handle the speakers? I mean the speakers can't be that bad. They sound alot better but for some reason the bass isn't really punching. Any ideas? Thanks alot!