honestly I wouldn't do anything. I often had this problem with my old Lupo but decided it was what it was and it was only silly to try and pretend it was quicker or sounded better than a 1.4. If you've ever heard a small engine with an induction kit (from the outside) it's very very obvious when they are flooring it as you can hear the vacuum of the throttle body being fully open but the car still accelerating very slowly. Unfortunately it only sounds good to the owner.
Problem with induction kits on smaller engines is that the factory air box is more than good enough (can easily supply all the air the engine could ever want) and is likely to give you a better cold air flow than an aftermarket kit. A panel filter you'd also be incredible disappointed with the noise change, as was I in the Lupo, there is none! If there is it's placebo.
For a little more grunt maybe you could remove the centre silencer as this would be fairly discreet however I'm not sure if this is possible on the 1.2
Your time will come so I would just be happy with what you've got
I personally prefer sleeper cars which destroy everything but look slow, get a DCI 100 not a 1*2
