They sound amazing! They add a great deep toned rumble... At idle it resonates really nicely. It has a great take off rumble and sounds even better as the RPM's go up. Its a great buy, for someone that wants a little more loudness and lower rumble. And if you add a Y pipe you can get a beastly MONSTER! Like this one here
370z loud. Z34 MONSTER - YouTube. But it is perfect as is, in my opinion... Not too crazy like straight pipes, but decently loud.