youngpak1

Hey guys, so ive been hearing a rattling sound from my cats on my 08 g37s. I found out my cats are on the way out, So i have a few questions.
1. Im not really looking into performance right now, but is it worth just getting HFC's instead of stock cats. (rest of exhaust is stock)
2. Any difference between AAM, Kinetix, Berk, FI?
3. Any other suggestions?
Thanks in advance!

blnewt

iTrader: (13)

As long as you live where you can get by the smog checks the HFCs are the way to go.
All those brands get decent overall reviews, I do know the FI sets don't have the mounting brace, so there's more of a load on them, but they are very high quality. There may be a few others that don't have that brace but not sure on that.

Baadnewsburr

iTrader: (3)

if you're not looking for performance upgrades yet confirm that its not just the heat shields on the cats before you replace the cats.

the heat shields failing on these cars is very common and causes most of the rattling that a lot of people report while the cats themselves are fine.

if its the heat shields, you can just cut them off with tin snips or try to bend the edges back so they don't touch the cats when they vibrate or you can clamp them down with large band (hose) clamps.

jpowersjr2

iTrader: (1)

Yeah to expand on what Hashim said, if you don't have a CEL and aren't throwing any codes then I wouldn't replace them yet. I wanted more performance so I replaced my working cats with ART pipes. No CEL since day 1 (3+ years with them on).

youngpak1

Ahh okay Im just waiting for some better weather where i can my car up and check it out but however, a little power wouldn't be bad thing haha. How have you been liking the ART pipes? drone/smell?