there are two cats on a b4.......one on the down pipe and one at the start of the centre section. as far as i know the one on the down pipe is the one to remove for power gains but im not sure if this is advised. i replaced my exhaust from the centre section back removing one of the cats and the car passed the nct but if you remove both i dont think it would pass
ps ye might introduce yerself in the first section.....
I have it done no problem once you map the car..if you dont map for it you will get boost spikes and w@nk your turbo..the one in the centre section is a silencer afaik
Talk to Damo in street performance,got a de-cat downpipe and centre section of him a couple of weeks ago and the difference is very noticeable nice sound out of her too