no muffler to muffler still cracking
#19
You aren't having loud pops like fire crackers and such are you? An air leak in the exhaust system will cause it as when you first let off you get some exhaust with unburned fuel dumped and it's hot enough that any oxygen coming into the exhaust pipe will allow ignition of the traces in the exhaust. Even if it happens ahead of the cats, you'll still hear it. Exhaust manifold or header gasket leaks can do it.
#20