Great video. I would be interested to see the effect on an NA engine; like the guys said, the intake temps after the intercooler on the R34 were the same regardless of the intake under the bonnet. I like the fact that they did all their runs with the bonnet closed, too.
In reality, I think with our cars the only way to the noticeable "10%" increase power they speak of is with dropping a Meg engine in, or approximating an R3 setup.