smoothing the box can cause stale air and reduce low down torque, making your car SLOWER
i know its a different car but on my old astra td i was told to smooth the airbox and take out restriction pipes to make it quicker, i tried it and at the hill at bottom of my street i put my foot down and was just changing to 2nd gear as i approached the top, but when i put it back to standard i was reaching 3rd gear as i hit the top, more power and better mpg with the oe setup
has anyone ever tested smooth v oe on a dyno? only ones ive seen have been oe vs dsg, smooth and filter in one go