I've done 3 trackdays with the HICAS intact on my '96 GTR. I haven't had a problem with it yet. I really don't notice the system at all while I am driving, but am very aware of it when riding as a passenger. That's just my experience, I don't think I can make a recommendation.
I do at least 6 track days a year in mine and i'll definately never remove my HICAS, my old skyline had it removed and the back end was always coming out, so its a great idea if you want to do drifting.
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