Pannel filter is ok and will give you a little edge, youll notice it pull to 80 mph and then struggle, unlike the std one which pulls to about 60 and then just stops lol.
i had a K&N in ym old 1.2 16v and it does make a difference.
IK's not sure about. i had a K&N cone at one point, a caf pipe and it had no sheld or anything lol. if im honest it make a fair bit of difference, power down at low revs was piss poor but up in the revs it was a little better.
i hear the vipers are quite good.
personally, for the sake of the fact your car is a 1.2 and itl always be s**t slow, get a pannel filter. no noise and a little extra power.