So, my mechanic fitted it as best as possible with as little leak as possible, then tack welded it and then dropped the entire exhaust to perform the full weld.
With the exhaust off, he suggested a pre-cat removal as to him the reason why the pre-cat had separated at this point was due to the pressure pushing it off as the pre-cat ceramic thing was not allowing the flow of gases through.
I said go for it (warning, loud!):
https://www.youtube.com/watch?v=gJVgPqaryL4Car is stage 1 already and that's it. Have driven 35 miles so far and holy crap the thing is so much more responsive to get going when you floor it and when it reaches the higher end of the RPM, like 4k+, it seems to deliver the power better.
Stage 1 definitely made the car feel more alive but this yet again has impressed me no end. As a person who knows not that much about engines, exhausts etc. it could be placebo, but it feels like a great upgrade for the cost... I dunno.
Only downside is that after giving it some beans, I can smell exhaust gases but not sure if this is a) a leak in the weld b) normal with this delete c) something else.
Other than that, it's a slightly deeper note up front and you can hear it in the cabin. I'm not of fan of deeper notes but this to me is acceptable, happy enough!