Its the worst place in the world to have it (although having said that I can now think of worse). The Subaru IC's suffer form heat soak quite badly so I have been told due to their position and when belting along because of the design of the bonnet scoop cols air is fed into the far end of the IC rather than all of it. I think you can buy kits for the scoop to split the air flow though *wanders back from going off on a tangent*.
Try moving it or better still phone Gav Wallace and ask him about the intercoolers he does. I have ordered one today and will be fitting it ASAP.
I fitted my new IC a couple of weeks ago. It is now in direct air flow behind the bumper scoop and made a big difference to the cars performance. I've now got used to the extra power though so I'm after more lmao When you actually compare the size of the original IC with the aftermarket version you can see the original mounting position is not the only hindrance, it is quite small aswell.