The sample rate of your I2C-mic will be quite less than 0.5Msps, I presume that it will be in the order of 20ksps, 40ksps when stereo.
The PSoC4 I2C max bit rate is 1Mbps which will be something like 100ksps (8 bit samples), quite sufficent for your application to sample and calculate min/max.
The mike interface specs -
At 24 bit 20 Khz spec makes sense.
Bob and Dana - Thanks for the help. I still can't get it to work. I've attached a file. If you could take a look I'd greatly appreciate.