I had a Pacestter header installed last week, and every since the install I hear a pop sound every time I startup it up. The noise comes from the muffler and there is nothing hittin against the body is the normal since that existing manifold is so restrictive. Also when I open my cutout the sound is not nerly as loud

i hear a pop every once in a while with just my catback. i have no idea what it has to do with, maybe it's unburned fuel in the exhaust system going BANG?

i know when i start my car my subs go bang once lol (poor ground)

I have no Sound system lol, but it does seem quieter after I startup a couple of times
Could this damage the engine?

sounds like a backfire to me..

well then my exhaust is causing my car to backfire.

Installed new MAgnaFlow muffler to replace the old Cherrybomb turbo muffler.It started off good when I left the shop but when I left the store it made the pop sound again.

I have the pacesetter installed for about 5 months now,I don't hear any sort of popping sound when I start up.

this is weird i just started it up again, it popped the first time but after that it starts normal