Marcos , removing the cats will definitely not bugger things up. Hard to put a number on the noise but I would guess mine is 50% louder when on the gas and just as quiet when cruising at any speed , also probably 25 % more burble at idle .hope that makes sense .
No matter what chip you have it will contain mapping for with and without cats . The appropriate map is selected by changing the tune resistor , you should have a white one that measures 3900ohms assuming you have a uk spec car , the one you need is 470 ohms 0.5 watt . These are very common and cost about 10 p each .
If you pm me your e mail I will send pics and instructions , can't figure out pics on the forum . I must get the kids to show me one day .
