I just replaced my Automatic compression releases and yesterday there was a slight decel pop but today I have a decel pop and what sounds like an exhaust leak. I can't pinpoint a leak but the exhaust sounds louder. I dis- assembled and re-assemble without replacing any gaskets but can't see a reason for decel pop for what i did. The only thing i can think of is the breather o- ring under the rocker arms might be the issue. Any thoughts?

 

Make sure you use a torque wrench on the header exhaust bolts. If one is different than it's opposite the flange may be tweeked and you may have a leak.

 

I would take a look at those releases, Sounds like one of them is sticking.

 

And what do you do to unstick an ACR?

 

I agree. Also always look at the last thing(s) you did before breaking into something else.
Most certainly not decel pop through the breather O-ring. You would hear it sucking both ways...