Fast road cams such as the PH3s etc. and a remap later and you should see around a 10bhp improvement, which you will be able to feel.
But keep the 300 quid you'd spend on getting the cam, vernier pulley, head gasket, cam seal, head bolts, water bump, cam belt kit, new oil and coolant.
Then the cost implemented on getting it fitted.
Then the £300-£400 getting it remapped to get it running at its full potential.
And drop an s lump in it, bigger bhp inc for less money, it gets said ALL of the time and people DO get sick of hearing it, but its so true. Ive been down the whole camming a vtr route, and ive ended up selling my cams after having a go of a pals STANDARD Vts because it was much nippier.
but its your car, so what you will.
Joe