I've noticed that whenever I warm up my engine or when I'm decelerating to a stop, my engine makes an odd noise at around 2500RPM to 3000RPM. It sounds like it may be coming from the exhaust. It sounds like a vibrating metallic noise, as if metal on metal were vibrating.

 

I've had this problem since I got the car (85,000 miles), my 1999 Subaru Legacy Outback Limited wagon has 97,500 miles on it right now, 5-speed manual, EJ25D.

There seems to be a resonance in that RPM range, and if the heat shields on the exhaust are loose (and I'd be really surprised if yours aren't ), you'll hear them rattling.

+1............I agree it is a loose heat shield shroud around the exhaust system. It doesn't cause trouble, just becomes an annoying noise. A lot written about this, and how to fix it. Do a search in our achieves to read what others have written

if you can find where the sheild is loose, you can tie a hose clamp to hold the shields tight. I have seen exhausts with huge dryer hose clamps all the way around the catalytic converter.

 

if they are horribly rusty, you can probably just rip them out. If you try to unbolt them, you are likely to break the bolts or rip out the captive nuts.