When you put in the radio, did you cut the harness or buy the adapter harness? It sounds like this may be the root cause of the problem. First, unplug the radio and wires and see if the fuses still blow. Bad news is that you may have melted some harness wires under the dash and created a short circuit. the harnesses are the same between the 323 and the Tracer. If you can lay hands on a Mazda 323 Shop manual (dealer manual, Chiltons and Haynes are useless) you will get everything you ever needed to know about the Tracer. They are good cars and their only weak point is the front wheel bearings, they are a PAIN to set properly. Drop me a reply if I can be of service.