I had (4) GMS MAF's, (2) were stock and (2) were "special adjusted" MAF's On the dyno 2 lost power, and the other 2 made no more power, I just read in Sport Truck that they could find no more power on the dyno either. I will say that my car felt faster with the GMS MAF (2000 convertible) but on the dyno no more power, or even less power.
I also tested 2 gmaf on my 2001 with no luck.I dynoed both back to back with stock maf and lost 10 hp and 19 tqe. I would spend the money on a proven mod. My car responded very well to halltech intake,throttle body and long tube headers. My trap speeds increased from the 115's to the high 119's and 120's.