Wow! Just finished reading through this entire thread. Pulled some really good nuggets from it. Thanks XR & to all that have contributed. This thread is very old but it's all fairly new to me.
Comparing sub specifications.
Alpine SWR-843D to the Alpine SWR-8D4 , what's the real difference besides the big price difference? I can find most specs on both but not all. Frequency response in basically identical. Both up to 200Hz.
I was also considering the Tangband W8-740P which XR touched upon. Frequency response on this is listed at 28-1Khz.
Hoping to begin my 2014 Cruze install in the not too distant future as I have aquired most all I will need. Still acquiring knowledge.