When my Stock MAF went bad on me I changed it out for a 75 mm Granitelli. I think I noticed a difference...not real sure..maybe on top end. But for the $200+ it costs, I'd do something else. Lower $/hp and now I'm looking at making other changes and I have to either get it matched to different injectors or buy another unit.
Gears are the best, if you can't get them and don't run a big sound system get underdrive pulleys. Those I did feel a difference.
