I had my Kinetix HFCs installed couple of weeks ago which is combined with my HKS exhaust (I love the sound) but I hear some kind of rattling noise when i smash the hell out of the car. Does anyone hear it too? I remember there was 2 bolts that the installer took out from the hood to remove the cats but i dont remember him putting any bolts back in there after he put in the HFCs. just trying to figure out if its normal

 

I have the Berk's and installed them myself; there weren't any bolts I took out from under the hood. it was easier to remove one of the bolts from the engine compartment but to install/remove there were 2 studs/1 bolt involved.

 

I have knetix HFCs with stillen exhaust 2003 coupe... I know exactly the sound you are talking about!! its the heat sheild rattling, you can hit it to bend it it back alittle, pounding it only lets you bend it so much tohugh, my mechanic removed the bolts from it, let it loose and bent it by hand, its not very thick matieral. then bolt it back. I still can hear some ratting when I gun it hard, but the rattling is much improved!~