X3 on cat cons.
By the time you get the noise, the cat is 90% empty and there is one piece that can't get out, and is bouncing around. Replacing the cat doesn't always eliminate the noise, sometimes there is a piece in the muffler.
97 T-Bird LX 4.6 - 80k miles
94 Supra TT Auto - street/strip car
04 CVPI- Brenda's car - 76k miles
95 T-Bird LX 4.6 - fully optioned, owned 15 years, 220k miles
96 Cougar XR-7 4.6- Brenda's car, owned 11 years, 187k miles
88 T-Bird 3.8 - first T-Bird, owned 5 years, 206k miles