help annoying pop in exhaust

It does have a header leak but that's not the pop I'm hearing.

When I installed cam I didn't advance any just lined up the dots

Factory pushrods were reused I can roll motor and spin all push rods with my fingers I haven't checked rocker arms with a feeler Gauge but I don't think they are to tight

The sound is more noticeable from the rear and only from driver side exhaust passenger sounds normal