Hey guys. Little info for starters: 2004 6MT @93k miles. Completely stock.

Back story (WALL OF TEXT WARNING)- I've been going nuts searching for an answer to the sound my engine has been making in higher RPM ranges for the past couple of weeks. It began shortly after the time I changed my spark plugs/coils/wires so for the first while I thought the sound was related to that - not true. It's similar to the various descriptions many people have had with non-premixed low-oil flow engine sounds - a raspy, rattle, maybe even growl sound coming from the mid to low engine(not SSV/MIAC sounds). However I haven't been able to notice any strong loss in power. This weekend some guys from our local RX8 club and I went up to Lake Lure, NC with some good fun curvy roads and heavy up/down hill driving. After the trip the sound has gotten louder and worse(once the engine warms up). Last night after some more spirited curvy road driving I pulled up to the house and stopped to look under the car to see my O2 sensor glowing orange(not fresh cigarette lighter hot orange) but definitely glowing. Today when the car was cool I went out to knock around on the cat/exhaust to see if anything was rattling or loose, this is what I found:



It seems as though the area surrounding the bolt holding my exhaust manifold up has rusted through and fallen a bit. I can wiggle the manifold/header up and down about an inch. Has anyone else had this issue before?

My other question is how dangerous is this for me to be driving? Is it hurting anything(besides my ear when it starts growling) to drive it like this until I can afford a header(thinking RB)? Worst case scenario I can find some way to make it stay up so it doesn't just fall off, although there should be more bolts holding it in place elsewhere. I do have exhaust throughput and air/fumes are coming out of both exhaust tips.

Thanks for any input, constructive knowledge and criticism is always much appreciated.

EDIT: I live just south of NC in SC, and we do not have emissions tests/inspections.

 

If it was your REAR O2 sensor, then your cat is clogged, gut it or swap it with a midpipe asap.
If it was your front O2 sensor, then the exhaust leak would have to have been venting straight onto it. I've never heard of the front O2 sensor glowing though.

That light grey/tan-ish colored metal there is just a heat shield. Mine is way loose too, and this does not cause an inherent problem, though it is obviously less effective than when it's solid and intact. Is that what is moving? If the end of the exhaust manifold itself is moving (the flange part with the rear to front bolts there in the pic) moves, then something is seriously wrong at the engine side itself. The exhaust manifold bolts to the engine in several places, and for the tip to move around you must me missing some and the rest loose?

Assuming you do have an exhaust leak for a moment, a leak itself is not inherently bad for the engine. It could give you problems with fumes venting straight there, and in theory you could get the "tailpipe flames", only coming from the crack in your header instead, which could be a problem.

 

Hmm, it was the rear O2 sensor( the one you see on the Cat itself under the driver side of the car).

And yeah, the light gray/tan material to the right of the bracket(where all the rusty spots are) is what is moving up and down, so that's only a heat shield? I believe that could be what's making the noise that I've been having, is it easy to remove? Is it recommended to remove? It's purpose must be to shield some form of heat, how much of said heat would I be exposing by removing it?

The sound I've been hearing gets pretty loud when it kicks in, but under regular driving just sounds like... I don't really know how to compare it, like how I would imagine spark plugs firing sounds like. A light buzzing/vibrating? I'll try to get some video of it tomorrow but with only my phone, sound quality is gonna suck.

EDIT: If severe heat shield rattle is what I'm hearing at high throttle/RPM(5k-9k in lower gears) then that opens up a whole new alley of threads I should start paying attention to - I'll see what I can find on reducing the noise and getting to the root of the problem.