You don't want one too long though. I tried putting ducting on an s4 I had and the temps actually increased as it didn't have enough power to move all the air in the tube.
Yes, I thought about this too. But I can always cut it) Anyway, I'll try it, this method seems to be good
And there is much difference in s4 and s7 design, where fans are placed, so I think ducting for s7 will be better than for s4