Its not sitting in traffic that is the issue, its pounding a track lap after lap where they cause issues, ask any GTR owner with a 100mm core who does track work....most of them have gone back to the standard intercooler so the motors aren't overheating after 2 laps.
The HPI kit for my Soarer is 2 1/2 hot side and 3" cool side, the Greddy and HKS kits are the same, must be a reason for it...but I doubt unless I am trying for 1200hp will I find out why lol