I just put on a new chain and im hearing alot of chain popping. I've loosened the slack with chain tentioners and still hear the noise. I also put on a new rear cog. Any guesses?

Wait until they get to know each other, then it should get better. Like sex with a new person. After awhile things smooth out.

Or the chainring is jealous it's not part of the new group.

Also like sex, make sure everything is clean and lubed.

Also, make sure that your chainring, cog, and chain are all the same width (1/8" or 3/32"). If it's a 1/8" chain on a smaller chainring or cog, it will make a racket...

and like sex...just turn up the Barry White and you shouldn't here the chain. (huh?)

Once I put a 1/8" chain on my 3/32" setup everything became silent. I think I just got lucky?

I'd double check the routing of the chain. It might be that it isn't quite right, and going OVER that little nub between the jockey wheels. It should not touch it.

There's also the possibility that you let your old chain stretch too much and it, in turn, wore out your chainring and/or cog. This is one of the most common ways to damage your drivetrain.