i recently installed a new exhaust system cat back. seems like everytime take my foot off gas i hear this rattle from 2-3k rpm drop. any ideas what or where this sound comes from? kinda sounds like a snore heres a video to help

 

I know I'm not helping by saying this, but every replica hks I've ever heard sounds like that. I wouldn't worry too bad, but ask someone with an hks rep and see what they say

 

Hard to hear a "rattle" in your video.You can hear a noise from the back
pressure when you let off the rpm's.I too have heard this on HKS replicas.
Its just the way it is.You pay for what you get.I'm guessing if you cut the
resonators open,you will see a difference in the baffles compared to a
real HKS..

 

Sell it and get a good exhaust. That is you're problem no doubt

 

nvm fixed issue, had nothing to do with the exhaust it was the heat shield from the stock muffler box that i never took out. thanks anyhow.