I've been in the tunnel in Genting, but I've not been in any other so I have no basis for comparison. However, it is definitely functional for flat flying. We easily had 2 and 3-ways in there. I was heavier at the time (210 lbs) and wore a baggy suit but had no trouble popping up a long way. You can even freefly in there. See the attached picture of czechbase. As always, the tunnel rats are very adept at making full use of the tunnel. When we were there, there was a Japenese couple doing some "serious" training. The great thing aboutthe Malaysian tunnel is that because most of the people who use it are whuffos, the tunnel rats really look after the skydivers who come along.