Wont do any harm at all mate.
But like mentioned the piping to the airbox is there so that the cold air from the front of the car can get to the airfilter as quickly and cooly as possible, removing the pipe will allow the engine to breathe abit better but will suck in warm air there by losing you alittle bit of power.
Hunt around on eBay and
www.performancecentre.co.uk and see if you can fine a induction kit for your car under £80 or so
You might also be better off just fitting a slightly noisey back box rather than changing air filters to get an induction roar might even be as cheap too to find a back box