How to make my 19908 audi a4 better??

I have a 1998 audi a4 with a full sytem exhaust and coil overs installed. When i drive over small bumps or anything the car is very sensative. I want to make it more durable for regular roads but idk wat i can do wit it. any suggestions. Also i want to put a sound system in it too if that is a good idea.How to make my 19908 audi a4 better??coilover and 17 0r 18 inch wheels with low profile (35-45) tires make them very twitchy because of the way the multilink suspension works, it will follow any ruts or bumps in the road, only 55 section tires and above give a really smooth ride on rough roads, try putting the tire pressures up to 36lbs or so and experimenting to see if you can match the suspension harmonics