Well, I for one did b/c I'm running nitrous, some may say its over kill but the way I saw it was I was doing cap/rotor/wires anyways so I just upgraded a little. Some things I noticed right away was how smoothly the engine idled and it seemed to pick up a lot faster and I'm pretty sure gas mileage might've improved some as well. Also, my stock coil had a nice hot spot on it for whatever reason which I think is what caused my car to misfire every now and then. No problems since.