Try looking at this post
http://www.contour.org/ubbthreads/showthreaded.php?Cat=&Board=perf&Number=331590&page=0&view=collapsed&sb=5&o=7&vc=1

From my understanding, the stock MAF adaptor is 70/75mm

Try http://www.duratecperformance.com/ and search for a MAF adaptor. It's easy, select the year, make, and model. That's it. A list of upgrades will come up, including the MAF adaptor.

Try these link for more info...
http://store.duratecperformance.com/store/shop.mpl?&Item=4
http://store.duratecperformance.com/store/shop.mpl?&Item=13