Mk1 Skoda Fabia VRS DECAT

Hi everyone, so im looking to get the cat cut out next week, what does everyone recommend, shall i replace the pipe completely with a new downpipe or should i just cut open the cat and take the stuff out and weld it back on? Also will i need to get it mapped as soon as its done or will i be able to travel somewhere to get it mapped at a later date to remove the fault code? Cheers