You fabricobbled a hot air intake?
Why?
I'd be curious for some data logs on MAF rate as a function of RPM and possibly IAT before and after the new intake. Unless you have some airflow smoothing device in the small space between the filter element and MAF sensor, the turbulent air can throw the MAF reading off (this is a common problem with all but two aftermarket intakes for the RX-8).
I had enough left over pieces from the one i made for my Jeep. so i figured why not see if i can make one for the Mazda (with the wife's approval. it is her vehicle). It did throw a P0171 code after about 20 miles. Checked the short term fuel trim with my odbii scanner and found it was running positive while idling. Figured this was probably caused by turbulence so i added some fins before the MAF. See Pic.
https://www.cx3forum.com/forum/attachment.php?attachmentid=21695&thumb=1
That solved the problem.
My wife has put about 400 miles with the intake, in all sorts driving conditions, and no codes, no pending codes, and no permanent codes. She loves the growl the engine now has.
I only checked the IAT's once and it was running about 10 above ambient (73f ambient) at a speed of 30mph. Obviously that will be higher when not moving. I did leave the "scoop" portion of the OEM intake in place just to help funnel air in to that area, don't know if that actually helps or not.