s2kjer

2012 IS-F, when moving if I tap the gas to accelerate slightly I get a thud noise coming from the back of the car. Does not happen when I take off from a stop. Has anyone ever had this happen or have any idea what it could be? I figured it was my exhaust but I just changed it a few days ago and it is still doing it. Thx

Onionboyz

iTrader: (3)

Aftermarket exhaust? After I installed my JoeZ I had the same slight thump sound when i tap the gas at around 2-3k rpm coming to a stop; I even created my own thread a while back. It's pretty normal apparently just a little back fire

s2kjer

Its hard to say. I noticed it when I had a custom Y pipe made for my exhaust delete when I first got the car. Now I switched out the whole system to a cat back X Force with no mufflers and I am still hearing it but almost louder. I think I am going to install the mufflers that came with the system and see if that removes or reduces the thud. If that does not I think it might be the mounts on something. Engine or diff

2008ISF

iTrader: (1)

Sounds like you are experiencing a backfire.

Car is decelerating, at the 2-3000 rpm range you give some throttle and you hear a pop. All isf’s do it.

s2kjer

You guys were right! I slapped on the mufflers that came with the exhaust system and the thump is gone! Obviously the ISF does not like muffler deletes... Lol