OK, I understand. You should easily be able to get 300 hp with a hybrid turbo. Call https://www.tmg-performance.com/
You will need their hybrid turbo, decent downpipe (the one I recommended will be fine) without catalytic converter if emissions is not a problem and no resonator, tmg or vw racing intake, wagner or tmg intercooler, tmg blow off valve, tmg remap, R8 coilpacks with the tmg adapter and thats about it. I would also get transmission remap with launch control and the tmg kevlar dag clutch pack. You can pm Queen, she can help you as she had a really powerful 1.4 TSI
I have written to her also to get her opinion. Well I don't know if you know about tvs engineering but with their software you won't need a new clutch. They are based in Holland. I have emailed those you recommended for the downpipe and are awaiting answer. I think the Wagner is way too expensive when I can get a bigger one for around 100 punds so I will go universal 550x180x65 at least . What about turbo muffler ? You haven't changed yours? And with the blow off you'll get that pffft sound right? Because that's illegal here. I also have to get sports cat for emission