80mm is def less restriction than 65mm.
They aren't just Z32 internals in a smaller housing because if that was the case, it'd max out way too early because the air has to travel faster through the smaller diameter. I reckon a Z32 sensor and circuit in a RB26 AFM housing would max out at about 180rwkw each.
Nismo's are def fine and if he said he had a standard airbox, that'd def be the go but because he has pods, it's cheaper and slightly less restriction than nismos and u get a set of brand new filters with the money saved.