Got a Honda K20 engine with close to 200k km on it. Somehow it has developed this rattling noise that happens when engine speed climbs up and down past approximately 2200rpm on the tach. Car is 7 years old and I don't recall seeing that much rust around the exhaust area last time it was on a hoist. I found a youtube video that's has the same sort of noise when the car owner revs up his engine. https://www.youtube.com/watch?v=ytBChDPLvZY I'm leaning towards a heatshield, but I thought maybe heatshield would rattle at even low speed and gets louder as engine speed goes up?