A triple core radiator would be useful too.
Having warmed up on a track day - it was two fast laps and one slow one then two fast ones again to keep the water temp down. No front mount intercooler and not running as much boost as most of you guys.
Also if you are planning on a full day of driving, spare front brake pads will come in very handy. I was shocked at how quickline the Skyline pulls up on the back straight for the hair pin but ate a set of pads in only four twenty minute sessions.