actaully it takes almost the same time ive noticed, if i drive under 2000RPM (becuase its cold) it warms up to full running temp at the same part of this road every time, both stock and CAI. but if you think about it, it should take a little longer becuase cold air is comming in BUT, cold air is also comming in from your stock air box because the plastic and stuff is cold as well as your RAD