I just got 2 used 300 Zx Mass Air sensors for 175 dollars, used. And it tooks some time to get them to fit, but finally did it. You can totally tell the size difference. I changed the setting inside my Apexi to the ''30''' engine. Is there anything else I need to changed over? Seems to run a hair rich at idle( I am getting a .9 voltage reading from my O2 sensors) and am wondering if I should lean out the percentage reading within the Apexi or the Milliseconds next to it on the injector screen? Seems to run real good! I wasn't getting a knock at all at 1.2 bar previous to this change over. Now I get a small one at around 7300 RPM. Hard to get one at my altitude, so little oxygen here (5230 feet, a little over a mile above sea level). Now with this extra air flowing I am probable maxing out my stock fuel injectors. If anyone else has done this upgrade please write respond to this page, with any help.