I think you are very unlikely to improve upon the original inlet design (assuming for day to day road use), fiat will have optimised this to deal with all weather conditions and so on. I also think that it is difficult to beat an OE filter it will efficiently remove as many nasties as possible with a low level of restriction. Performance filters might offer small flow gains though but whether you would really feel any difference on a relatively low powered road car except for a placebo effect is, I think, doubtful they may offer longer term savings in terms of being washable I suppose but if they let more particles through long term engine wear might be slightly increased.
