When i play my stereo loud i can see the dispplay on the radio fade away on the beat. Does that mean the battery isnt strong enough or something?

Its usually the sign of a weak electrical system. Best bet is replacing some of the ground wires(running from the alt,cant remember the other ones honestly) with a lower gauge to increase performance. You could also get a higher output battery and a cap if you really want to. I bought a yellowtop thinking it would help a bit which it did,but its also a nice thing to have just in case.