There is some Raspyness to it but not really bad at all and no hissing noise, I also Have Berk Test Pipes....
This set up is even better than the one I had on my 06 350Z which was Megan Headers APS Test Pipes and Borla Exhaust that had a raspy noise and a hiss on decel...
I think People will be happy with HKS and any type of Test Pipe/HFC but then again its all in the persons ear
DAN