Just because of the age of your car, and from having owned an older GP myself, you might want to make sure the speakers are still .. good.

My old ones were .. well, old, and greater degrees of bass in this young people's music made them crackle and other such miscellaneous noise. I swapped them for some Sonys and they didn't do it anymore. I didn't do anything to the old wires or any grounds, and didn't do any amp stuff.

Was Bose an option for 98? Just wondering.