[kabukiman]

I've discovered the source of a metallic ringing noise I get when accelerating is my exhaust.

Some part of it under the car after the flex joint is resonating badly, almost like a hgh frequency rattle.  It is intermittent.

I have also noticed when the noise is the worst/loudest, the car sems sluggish and pings, even on a cold day with premium in the tank.

This leads me to believe a part of the exhaust internally is broken and maybe blocking flow?

What ye reckon?  I'll go to hyundai next week probably

[Phil №❶]

Well it could only be in the rear muffler or the Cat converter, the rest is just plain pipe. The muffler is made with internal welded perforated baffles and if a weld breaks its usually an unmistakable metallic rattle which is most pronounced at a fixed rev range due to resonance, not high pitched.

[eye30]

check the brackets etc.

you may have hit something and bent a bracket which is causing the exhaust to rattle or vibrate against the car structure