It definitely sounds so nice when you hit Mivec or when it reaches 3500+ RPM. With normal acceleration, the sound is not ridiculously Loud. It growls only when accelerating which is still very stealthy until you put some gas on to it. Its quiet when cruising. Yes, I noticed it improved the power from mid range and highs and I can feel it pull. You’ll love doing a pulls under tunnels/bridges, its so LOUD, it’s for sure fun and feels sportier after this mod.