Don't think you can re-map most chips/ecu's. Only the Unichip can have that done. It involves re-programming ecu to react better to the cams, exhausts, etc.
For a new chip you need to take car to a performance garage, to be chipped. (unless they have a specialist) they normally then remove ECU and take it to a fella who solders the new chip in place.ÂÂÂ

AP Performance near Leek quote a bargain price of £220 for doing this. In theory a good condition 16v ABF engine should then produce close to 180 bhp. Prices can be upto £400 depending where you go. All being well, within two weeks I'll be getting this chip, and I'll let you know how I go on. Just sorting out some minor problems 1st.
The standard cat, I would guess, will reduce bhp by about 5bhp on a 16v, so a de-cat or free flow will make a small difference. Personally I'd keep it standard on a non-turbo car, for reason of mot or cost/hassle, etc. An exhaust place will fit/replace it for a small charge. Its dead easy (if you have a ramp or a pit in your garage!)