I just started noticing this "squeaking" sound, sort of like a rat lol underneath my car whenever I rev between 3-3.5 RPM. I am due for a replacement cat since it rattles pretty hard. I am also wondering if this stupid squeaking sound is also the cause. It only happens when I rev from 3-3.5 then goes away. I tried to listen to it as best as i could and it seems to be coming from right underneath where the clutch is, underneath the car. Anybody have any input?

 

A squeak? A doubt a squeak could come from a cat, so why not just replace the cat since its bad and just take it from there