Cars tweeter is crackling
 

Recently I installed a new stereo in my girlfriend's 2003 Ford Escape, and when the volume is turned up just a bit too far, the tweeters start to crackle, especially if there is a lot of bass. I have seen a decent amount of posts with this issue, but I have a hard time following them as I dont have too much knowledge pertaining to electrical wiring and speaker systems. I spliced and installed the stereo properly, and the speakers in her car are all stock. Basically, do I need to change the tweeters? Do I need to check out the amplifier?