Exhaust sounds wierd, Any ideas what this may be? Options

[Tweek]

I recently had a new exhaust system put in from the cat back. I mentioned it before about how the guy told me that the cat was connected to the header, and someone said that we have two (one connected and another regular one). So, I have'nt put it up on a lift yet to check it out, but thought that he may have just taken the second out.

The problem is when the engine is cold and I start it up, the first couple times I hit the gas I hear this sound coming out of the back that is wierd. Its kind of a crackling, clicking sound. Hard to describe, but maybe something like the sound a stun gun would make. It goes away after a couple revs, and only happens after the engine is cold.

It dosen't seem to effect the performance at all when it does it. Any ideas what this might be?

[hyp3rk1d]

thanks.. i really appreciate it...

ne suggestions now