Well to clear things up
First off with air- intakes it's about surface area, tHe bigger the surface area the less flow restriction.
The Best air-filters are the original car makers Cotton /paper mix, Theses are harder to come by as Mazda now make alot of these comon spare parts in Thailand, so you will find more repco stlye treated paper type elements.
THe difference between the Cotton/papaer and the Cotton treated, K&N is that the K&N uses the oil to filter the tiny particals of dust & dirt where as your Cotton/paper element uses the Paper to filter it. This is where the so called restricitons apply but ideally you should wash it out every month in dust areas and every 3 in city use ( daily use make it every 2 as them dam trucks kill and if you have a low cold air-feed into it as well)
Codl-air works it's been used from factory to racing. Any air out of the engine bay is colder and be it forced in by movment in travel or be sucked in by turbo, by the time it is heated by 1 or 2 degrees it's still codler the nthe 10 degress to 20 degress above in the in engine bay.
This in turn menas codler air is heat by the turbo but originally starting colder menas it is not as hot when it comes out.
Comes in at 20 degress ambiant Plus 70 from heating making 90degrees
but if it's 35 in engine bay air + 70 from heatign making the intercooler have to intercooler 105degrees of heated air.
The pod makes KW"s top end only due to less ristriction due to more surface airea but if you factroy Panla has large surface area it's not that big, 626/MX6 1st gen fairely large not huge like now BA or LS1 but big enough, If useing factroy turbo don't worry about it , as you will not see 1 difference between K&N & Factory maybe 1KW at top end but not consistant.
We did our own dyno report stock Type R made only 3KWs more when whole air-box removed no filter at wheels 3KWs nothing. Put me in driving and it's going to still lose .5 seconds on the quater over the owner = weight 100KG vs. 65KG
With pod it still lost 3Kws or lets be real precise 2.5Kw's but in the enigne bay it would loose more due to heat in the intake.
With the in take to the box removed we regained 1.7Kw's or 2.Kw up top.
Which really means crap all.
You question to Pod or panel, my soultion has always been follow the pros and the men in white coats.
Holden offer with Holden by desgin, exhuaust cold air intake on the LS1 which with proven results on the engien dyno bring it up too 275kWS on a SS 235KW motor.
The real difference is in the intake snorkel it's bigger overall has a bigger hole to suck air into.
Look at the group A Gibson motorsportGT-R 2 large boxed panel filters with large cold air-intake feed.
Group A VP commodre same thing 2 lagre, each corner behind the headlights, with big feeds.
So before you put a Pop on think do you want showy pod with lost of noise for that true Monica sucking noise
Do you want best perforamce with no noice Panel and cold feed.
Or do you want ot be nuts and just use notihng at all.
Thne again you cna just remove the silencer from the factory intake, inside the gaurd gives you more noise and still faactory intake which on the 626 works better then mx6.
Sorry about spelling, I'm in my tafe which joins onto this high school and the new year 11 have arrived, my eyes keep wondering