On a stock Integra, you can't hear VTEC when it activates, but you can hear the IM butterflies open at 5700 rpm's. Many people confuse that with VTEC. VTEC activates at 4400 rpm's on a GSR. You can't hear VTEC itself until you do some mods and open up the engines breathing. My very first mod on my GSR was an AEM CAI, after installing that I could only barely hear VTEC, you had to really listen close. Then I put on an Apexi WS exhaust, no change. But THEN I installed a header and a high flow cat and you could definitley hear it then, I thought it was such a fucking cool sound, I loved it. The engine just gets louder when it happens, and you can hear the extra air rushing through the engine, its beautiful. The stock header kills a lot of the sound of VTEC, just about all of it, really (Honda made it that way on purpose because most people want a quiet car and wouldn't care to hear VTEC turning on). Then I installed some cams, and VTEC was even louder, AND since then when it activates there's a pop sound. Before I installed my cams, i heard alot of people on Honda boards saying that when VTEC activates on their cars there was a popping sound, but I was like "what the hell are you talking about, mine doesn't pop at all", then I installed my cams and knew exactly what they were talking about!
You don't need to drive a VTEC car any differently, although I do. I don't take my car into VTEC range unless I really want to because it kills your gas mileage. The engine dumps more fuel since your adding more air.
