It backfires when i rev when the motor is still kinda cold. Is this a sign of running rich?

 

What are signs of running rich?

 

If the air pump solenoid hasn't turned on yet (it doesn't until the car is warm) you may get a slight backfire due the fuel mixture being rich. I noticed that with mine until I heard the air pump turn on.

My .02 cents.....

 

Is it backfiring or is it just popping from the exhaust?