To answer the original OPs question (like 2 years after the fact lol): the Bose upgrade is hardly any better than the crappy stock audio. You're way better off going aftermarket.
and while I'm on the subject of sound, I love this car to death but the audio system is absolutely unforgiveable; got in my bud's Si the other day and was blown away by the sound quality compared to the Z. I think it's a little embarassing that a Civic with "Honda premium sound" has a better sounding system than our beloved 370Z.
