ok im going to try and explain it to the best of my ability.......
well when i am going up a hill n 2nd, and keeping it at 2k-2.5 rpms, i hear a weird tinging noise like something is loose, or its compared to the noise of a rattle can being shook
well i dont have the cat underneath its the one by the headers, and that heat shield i tried to take it off a few weeks ago, and i couldnt get the sensor off, so i just re tightened it back down.... hmmmmm
What kinda engine you have? The early GSR manifolds were notorious for that. Mine used to do it all the time until I upgraded to a race header. But yeah tighten up heatshields and inspect for cracks etc.