Malakas

Thanks to all of my "online mechanics"!!

It seems as if the consensus is an issue with either a loose heat shield (perhaps not
tightened after coil pack install), or an problem with one of the cats.

I will have it checked by my Indy asap. I needed front brake pads and an oil change anyway...

If it is one of the cats, and they are no longer in warranty (no cel), then it might be time for cat bypass pipes!!

SH || NC

Also check the 02 sensors; make sure one or has not backed out somehow. Otherwise, sounds like what others have already suggested: heat shield or loose tip perhaps

Pac996

My original plan was to say I couldn't name that tune or band. But.......hey good luck getting to it. That sound isn't anything any of us would want to hear on our cars. Best of luck.

Malakas

...update...

Well, I crawled around a little bit under the car and found a loose bolt that holds the exhaust can. After some contortionism, I was able to tighten it - but didn't have time to turn it on and listen...

I also rubber malleted the cats / exhaust etc - no sound... curiously, the OEM headers look more like the picture of the X51 headers... so thats cool (never paid attention before).

Hopefully this will be it.

gota911

If one of your cats looks like this, then it's been blown.... !

Malakas

- thanks for the input Tim!! Lol!!

Noise is GONE.

Hard to believe a bolt with 2 turns of play, could make that sound. Maybe a good time to bypass the cats anyway, you know, as a precaution...

thanks to all

gota911

Glad you found the cause of the noise!

ivangene

if you had removed the bolt you car would be lighter AND it would never rattle again