cyi1

2006 Z06 with Corsa exhaust.

So I've had this rattle for a while whenever I give more than 70% throttle. Turns out that the flange where the cats and h-pipe meet are tapping the metal heat shield under the car. It's causing the whole center console to rattle during hard acceleration. It even rattles under normal acceleration when the exhaust pipes are cold.

I took it a couple muffler shops and it looks like my options are:
1) Buy headers / x-pipe / high flow cats. This will eliminate the flange since setups like the LG products are pretty much 1 piece with just clamps. This is the most expensive route since it would cost around $1800 in parts
2) Have a muffler shop cut the flanges off of the cats and weld them on so that the parts where the bolts go are turned towards the sides. This way they won't touch the body. Or have them just completely cut off the flanges and put clamps or something.... This should cost a couple hundred at most.
3) ?????????????

I don't know why it's doing this because I doubt it was doing it with the stock exhaust on. A local Chevy dealer told me the H-pipe isn't exactly level and so the end towards the front is angled upwards. They believe that this is why the flange is able to touch the body. The car has GMPP but they won't work on the exhaust piping because of my Corsa exhaust.

BTW - The left muffler on the Corsa is very easily movable while the right one isnt...

Not really sure what to do....


But while I was under there I happened to see this which seems pretty cool.

sshaggie

What route did you end up going? I think I might have similar problem on my '06 Z w/stock H Pipe & Corsa.

cyi1

There was a temporary solution where a friend grinded the top of the flange a little but the rattle eventually came back so the only solution was to spend 1000 on used American Racing headers + install + tune... Cost a lot but worth it

sshaggie

Okay, thanks for the info. I'm hoping I can loosen everything up and gain enough clearance to make the problem go away. If not, there is always the header/xpipe route!

20psirabbit

I've had the same problem. Stock exhaust with stock tunnel plate, I had no problem. I put on a EE blanketed tunnel plate, the banging started from the h-pipe and tunnel plate at the flanges from the manifolds to the h-pipe. I put a zr1 x-pipe on the car and it banged even worse. It seems the zr1 x-pipe flanges are bigger than the h-pipe. I swapped back to the stock tunnel plate but it didn't stop until I did some massaging on the flanges with a grinder. My BB Fusion also knocks against the framerail and/or the diff heat exchanger in the rear.
It's been extremely frustrating, I'm going to try swapping to Hinson poly motor and diff mounts to see if that helps, I can't think of any other options.

tjwong

What year is your car? I had a customers car in my shop that did that very same thing. We took the car to the dealer and under warranty they replaced both CATs. Problem solved, this was a 2009 Z06 that was bone stock. This was the only one that I personally saw but have hearad of a couple others that had the same issue, now yours.

20psirabbit

Mine is an '06

Jtirwin27

Does the same on my c5. Must be a design flaw. I have got he tips alligned and tight but still cant stop the rattle underneath. Irritating as crap

Lawdogg

loosen exhaust manifold and all center section exhuast clamps. Pry the spot that is rubbing away from the heat shield and hold while everything is tightened starting with the manifold. This solved the identical problem on my car and took less than 1/2 hour on the hoist.

20psirabbit

I did this already, it got me a little more but it was still banging on the EE tunnel plate as well as the stock tunnel plate with the zr1 x-pipe until I ground the flanges just a touch. I haven't tried the EE plate again yet, I got tired of pulling the midpipe over and over again.