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Z MAFs are only good to about 500hp. But since we have dual throttle-bodies, Z owners can overcome this simply by doubling the airflow path and changing the values on the ECU.
At least on our cars, there isn’t a reason to switch to speed density. There are Zs with 1000+whp using stock MAFs.
Here you can see between the headlights, two ‘u’ shaped pipes. From the factory, the MAF would sit right in the middle where they come together. But here they split off under the bumper where 2 air filters are attached, but only one side has a MAF.