So I decided to upgrade the standard speaker cables that came with my Z5500's to 3mm Monster Cable. While it just-just fitted into the satellites (with my bad solder tipping) I only discovered afterwards that the clips on the sub are smaller than the satellites, so I really had to work hard to get them to fit. So in future if you want to attempt this I would suggest 2mm rather.
Here are some pics of the cabling being pushed into the trunking. It was a tight fit! I tested various method to fit 3 sets of cables in and the best was stacking them and forcing them into the trunking at the same time.
Got the Wii up and running as well