2000 mustang 3.8L Wierd Exhaust noises

[Faststang48]

i have a 2000 3.8L with aftermarket clutch, CAI, Exhaust, and other things. My exhaust just starting making this wierd noise today... i do have an exhaust leak but it is different from that, it sounds like a tuner, and its rattles on the rear passenger side... if anyone has an idea id appreciate it. and if it would help i can email a clip of the sound...

update (4/21/09): i lifted the car and examined the mufflers and exhaust system... i found a small three cracks in the passenger side muffler... im goin to replace them but i need a temporary fix.... any ideas? (bty they are flowmaster 40 series mufflers)