Uhm, your B&W speaker's bass response is going to be a limitation on the design of the woofer (i.e. xmax, free air resonance, etc.) as well as the design of the cabinet/port. That being said, you can get stronger bass when you use speaker wire with larger solid-core conductors. You could try looking for some older Audioquest Midnight speaker cable. This is often available on ebay or usaudiomart.
http://www.audioquest.com/archives/speaker_cables/spiraled_hyperlitz/images/midnight_c.jpg
The Midnight is a 10awg cable and uses three 17awg conductors for each leg and has very strong bass transmission. Alternatively, you could also try something like Audioquest Type 8 if you want something newer. Type 8 may give you better resolution overall, but maybe not quite as strong bass.