There is a horrible rattling type noise coming from the exhaust header where the flanged/donut that attaches to the rest of the exhuast. I am 100% its not a loose heat shield, and this problem only occurs from 3200rpm-34000 rpm. I took the donut out, and it rattled at every 1k rpm. Tried a diferent donut and rattled now and then, the best i can do is use the stock one and just let it only rattle from 3200rpm-34000 rpm. Any one got any clue?? Is there something special that occur around 3k rpm?? Oh yea, the car is a sexy 97 gsr.

 

just take the heat shield off i had that problem and i took it now it doesnt make a rattaling noise but i cant park on high grass

 

had the same problem especially when cold, cat was cracked.