my 200ci "pops" when decellerating
 

I recently installed clifford 6-2 headers on my '66 200 mustang. I haave two glasspacks in dual exhaust. Now, since the exhaust is much louder, whenever I decellerate, I get this "popping" noise from the exhaust, similar but not quite like a backfire. What is it?? Is it incorrect exhaust pipe length, incorrect backpressre, or valve timing or somthing???

I'm not sure why it does this. But is just does

Every vehicle I've seen with louder type exhaust does that.

It's not anything to worry about

yeah there is a chevy pick up here that just got a bunch of exhaust work done and it now does that popping noise too. i wouldn't be worried by it either