Stereo

[VES]

I've got a 98 boxster with the upgraded stereo, Becker 210 with 6 speakers and amp. My questions are: does my unit have speed dependent volume control, and if so, how do I turn it on? I'd also like to add more bass, and am thinking of just putting a 6" bazooka tube on the passenger side footwell when I'm driving alone. However, I look at the existing amp setup and it looks like it's all put together with wiring harnesses, any idea how to figure out what wire is what? The reason I ask is that I'm thinking about replacing the factory 4 channel amp with a 5 channel amp (one channel being a sub output), and then only having to figure out how to get one wire back to the sub. Last, how good are the factory speakers, and is it worth worrying about to change them to a name brand aftermarket component system? Thank you all for any responses, I'm just getting started with this car, as I bought it used a month ago.