I am new to this forum. I just owned an SPORTIVO 2007 AT and so far I am very satisfied. I am just wondering if some of you would tell me what audio set up would I need to improve the sound as I found it to be lacking of bass. I am thinking of buying a sub-woofer to improve the sound but I don't know where to get it and where can I get it the cheapest. How much will I be spending? I noticed also that there is a space for additional speaker on the left portion in the third row. Is that intended for an audio upgrade.