I finally got round to getting a new MOT on my faff yesterday and it passed with only an advisory on the back brakes which I knew were needing replaced.
So as soon is I got back I started ripping out the cat which was a pain in the arse on its own! I managed to depressure the air con system at the same time

lol while the decat pipes been off I used some heat wrap from my work to lag it and a few jubilee clips to hold it on. I took the car for a test drive and while sitting at traffic lights in the middle of traffic loads of smoke started to pour out of all the vents in the bonnet

thats when my heart stopped and I thought oh crap the heat wraps on fire!
I opened the bonnet and it just seemed to be either excess gasket compound or maybe a coating from the wrap and one of the jubilee clips has melted the coating of it lol but thankfully no fire.