It goes so far beyond the obvious parts that you'd think you need to replace. Even if you could drop in a TFSI (sounds simple doesn't it), bolt on some bigger brakes, and off you go, it'd still be a lesson in false economy.
I know it's not the answer you wanted, but it's just the way it is.
And big power isn't the be all and end all. Either accept you've got a 1.4 and strip it bare by 200kg, polybush it, change the final drive, ohlins suspension, nqsbbk, semi slicks etc...
Or stop in your tracks, sell up, and buy something else.
Best quote I've heard about modding and 'getting the bug' was:
"If you want a fast car, buy a fast car".
Funny thing about this, as much as it's true, is that it still applies to cars you buy that are already fast, if you've got the bug. I'm at Stage 2. Is it fast enough? No way. Bigger turbo next. Will I get desensitised to the bigger turbo and then want more and more? Definitely! It's all relative.
So, without babbling on too much, try and love what you've got. There will always be a car with 100 more horses. Trick is knowing when to stop pining for it.