is your box ported? if it is then you dont want to use tones too much lower than that. If you're in a sealed box then you should be ok.
Pretty much all Sony product's are as very good. I have a Sony Xplod player in my car that is really nice and I have a Sony TV in my bedroom that is almost 20 years old.
Please, No! Sony does not make ANY sound quality-worthy car audio products. Check out TC Sounds, JBL, Infinity(referance series only), or Kicker for good deals on woofers. NO other brand holds more competition records than Kicker. You can get KickerC...