I'm going to go out and just recap what I said in that original topic I linked too
Initially I thought wow and yes, the car was more responsive and it did sound good, then again I had also installed the SS exhaust as I remember.
I got hold of a VT Clubsport airbox for 20 bucks, which has the 2 hole mod already done from factory to allow more air in, and stuck with that.
Honestly, once the car adjusted itself to the new air flow I felt nothing. The induction sound is still there, but the punchyness is gone.
As for fuel economy nah, its not anything overly impressive. 750 kays @ 8.3litres/100kays is really good economy, this wont do squat for it. Dont forget, the dash calculations only involve a rough guess, ie litres of fuel in tank verses total size of tank, divided by average speed or something stupid like that. If you want to try it, set cruise control on a freeway (100 to 110 zone) then reset your average. Just wait til it averages it out, you'll have like 3.9 litres/100 @ avg speed of 110 kays, and it'll stay low until you reduce your speed then climb high quick smart and WONT go down quite as easy.
The dash cant even calculate the remaining amount of fuel in the tank properly anyway, so I'm highly suss of the fuel average readout to begin with, let alone bothering to try and make it say anything lower.