A couple of thoughts:
1) I believe that the CP-E CAI is the best intake money can buy. It is a CAI (yes, intake temps do make a difference, the ECU does not ignore the IAT sensor) and the machined MAF housing is a thing of beauty.
2) Don't look at A/F ratios because the fuel system is usually running closed loop. Check the LTFT's instead. For example, if the intake had a leak after the MAF sensor, the ECU will try to compensate by adjusting the fuel trims. In this case, the A/F ratio may look normal but the LTFT's are going to be way off. At idle, the LTFT with a CP-E CAI is usually less than zero (i.e. a negative number). If the LTFT (at idle) is ever greater than +/- 10%, something is wrong.