I installed mazda's CAI and the performance exhaust and have noticed some popping (backfire) when I'm shiffting at high RPM's Is this normal??? could it be runming leaner now that there is more airflow to the motor. I have aslo noticed the motor kinda stumbles a bit when I start it in the morning.

Any thoughts anyone

 

The stumbing I am not aware of, but the rest is certainly normal to mine.
The backfiring/popping seems to largely dependon how fast you back off the gass pedal. How much unburned fuel isallowed to collect in the exhasut system. It's not lean mixture that's the problem, but unburned fuel allowed to enter the exhaust.
If you back off easier (not during shifts of course) you will notice a difference, I'm sure.