I am currently driving a 2007 G35x. Being a poor college student I did not want to pay $300 or $400 on an intake kit from K and N, Stillen or weapon R, so I decided to come up with a custom setup. I purchased 2 K and N, 4 inch performance intakes, 2 spectre 4 inch MAF adapter tube, and two 4 to 2.5 inch silicone reducers. I just removed the stock air box and slid the reducer into the same tube where the stock intake came out of and tightened everything down. The first two attempts at starting the car resulted in the car stalling. The third time the car was able to idle but my dash looked like a Christmas tree, and the idle was rough.Throttle response was very poor and the car went into limp mode and would not let me go above 2500 RPM. I plugged in my code reader and I got a P0102 code which has something to do with the mass air flow sensor. I took the intakes off put the stock back on and the car ran perfectly fine. Don't know where to go from here, the only other thing I have done to the car is a muffler delete which has sounded really nice but I want to get the intake situation figured out. I am used to working on older cars, so I just need some help better understanding possible issues with throttle bodies, computers and sensors.

 

You need to use the stock MAF housings, the computer is tuned for that diameter. You can change the diameters just not thee maf housing

 

Has anyone tried ever tried the Tenzo-R air filters on our G35's, price is a lot lower then K&N or Stillen.
Official they are made for the 350z, but i think they will fit on a G35 too.