ummm if im not mistaken on this subject secondaries are only on vtec models, and those secondaries opening is what makes the "vtec noise". if im wrong im wrong but i dont believe i am. oh and on the vtec noise i never even really noticed mine on my gsr until i put my sri on and then i really could hear it

edit: to understand it maybe u should check out http://auto.howstuffworks.com/question229.htm
that will tell u how vtec actually works...