Okay, i have this strange rattle with my new motor.

The exhaust consists of eldebrock headers, and a flowmaster catback(barf)

If i bring the rpms up slowly, no noise what-so-ever. If i quickly punch the gas, i get this tinny rattle noise. I have already removed my heat shield from the cat, and when i pound on my cat i hear nothing.

Any thoughts on where to look, wouldn't a muffler baffle make a deeper noise, this is a real tinny sound.