Question on Exhaust Noise

[pelsteve1]

Here is another issue I have had pretty much from day one on an 01 S, since acquiring it bout 4 years ago.

I hear a rumble on the right side. Its most prominent when I downshift from 3rd to 2nd. The issue I have is, since I have to drive the car, I can't tell exactly from where it comes, but I suspect its either the front or rear cat cavities, but NOT the muffler. It seems that is too far back and not consistent with where I hear the noise.

I don't really have any rumble at idle or accelerating from what I can tell.

I do not have engine light on and have been passing smog in Nevada.

Has anyone come across this issue??