or maybe just you were unlucky and gear box was gonna go anyways.. a new turbo isnt gonna kill your box, plenty of people go put 300 bhp through a mk4 box and im sure theres would go straight away if yours did. just check gear oil, remove the 17 mm allen key out of the front of the box and if oil runs out its fine. if loads of oil runs out quick its over full so let it go till its slowly running out the box, check the oil in the box for bits of metal, but like a guy said earlyer on here not your cambelt over tight is it? your mate know owt about cars?,