I didn't know that about GM. Just wiki'd it and it sounds pretty neat. I had the lightning mafs in mind for late-model american parts. The lightning should be good for around 700hp.

Just one word of caution about using these large diameter mafs. They have a tendency to be pretty crummy at low airflows, including idle. The volume of air is very low, so the intake pipe shape, distance from the turbo (if any), and filter setup can have a big effect on the accuracy of the reading. Air can be diverted around the element so that it's not read, and it can also swirl through the element making it read high. These can be tuned around to some degree, but they're best avoided.