It's the most annoying answer to the question and you'll probably disagree but save the money. I had a mk2 1.4 which I spent a small fortune on, its now 2 years later and I've got a mk3
Cupra but the money would of been so much better spent on my
cupra than it was trying to make my 1.4 better. I'm only 19 so know what it's like but honestly mate I'd save for something faster. But if your determined to mod, I'd get a second hand system and a reducer to make it fit, I went the custom route on my 1.4 but it sounded like world war 3.
Hope this helps.