My Murano has the upgraded stereo system with the 6 speakers and subwoofer and the highend sounds muffled to me. I have the treble up as high as it can go and I've backed down the bass too. I had a Bose system in my '95 Maxima that had the best sound I've ever experienced in a car. It had terrific clarity and crispness. The sound system in my Murano seems to be missing that. I'm thinking about either adding tweeters or replacing the speakers in the dash. Has anyone done this?