Bending cord which just fits really tightly gets far superior results, if you can work it far enough down with washing up liquid or olive oil twist it as you go then it will be perfect. Sometimes if it's too tight the cord will get stuck inside when making multiple bends so try to work your way towards the end pulling the cord out as you go.
The best toleranced cord i've had was the primochill one but that's out of stock now, monsoon was miles too small although as a positive it would always fit in any tube. Tube can vary too in all fairness.
Which cord did you get the XSPC? I'll try out whichever is in stock at OCUK tomorrow and let you know, I need a new cord myself. The primochill one is black and indistinguishable from a power cable so I keep losing it
JR