My '96 had 10 ohm speakers in the front doors. Just upgrading them to Kenwoods at 4 ohms (just about every speaker in the auto world is 4 ohms) made a huge difference in sound output and quality. I can actually hear my music when driving at over 100 mph now. I didn't change anything else. Just upgrading your factory speakers will be an improvement, especially the front ones. I beleive that the size in the doors are 6 3/4". Check out
http://www.crutchfield.com to compare specs of components.