2001 impala Amp

I am curious do all 2001 impalas come with an Amp? I havent looked at mine to see, but since I had my battery changed. The battery that was originally in it would cost something like 80 bucks to get one just like it to put back in at the time I didnt have that much, so I had them put in a cheaper battery.

Well since the cheaper battery I notice my radio hmm doesnt have as much hmm well bass to it or something. Could it be because of the cheaper battery? And also how do I know my car has an amp built into it? Is it underneath the back speakers in the trunk?

In my 02, it's in the trunk between the speakers

It should be between the rear speakers under the rear deck. Had a problem with mine and took a couple of years to get the dealership to agree. They replaced it and no more problems. Plenty of bass now.