Hi everyone, I own a 2004 is200 se auto-very smooth. The head unit loads the cd, s at the top,model no:13909 this produces a good detailed sound but seems a bit bass light. My previous 2000 is 200 se the cd, s loaded at the bottom model no:13902 this head unit produced more bass and to me gave a better sound. Could I fit an earlier unit or amplifier into my car? Any help or advice please.