Well, I'm 99% sure it isn't the intakes at this point - I checked those out today and they seem quite snug in there. After that I took her out for a spin and the sound is still there. It seems to come from the passenger side rear. Doesn't make alot of sense because the exhaust has been on the car for months and I haven't heard anything like that before.
Is it possilbe this is some sort of break-in period thing with the HFC's? I guess that doesn't make sense either because the sound only happens when the car is in motion. Guess I'll spend some time underneath the rear this weekend and see if I can see anything that might have shifted while installing the cats.
Not really interested in starting to swap old parts back in to see what makes the sound go away but it may come to that.
