You should not have any problems taking a stock GTS-T skyline out on the track..
Just make sure the oil is clean, brakes are in good condition, your radiator is flushed, and filled with decent coolant. All else is optional and is really about improving times. I'm serious.
Your car in factory form should not overheat, blow anything up, or throw you off the track. HICAS doesn't help, but it won't kill you either.
It can depends on the type of 'track work' you are doing however... how many laps per session and the like. That can make a bit difference to the overall heat in the engine, which is the main thing to be careful of.