Alternative power-plants and transplants (GTi, Porsche, Subaru, Audi, diesel etc). Discussion and Q&A last answered over 2 years ago.
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In my opinion the gearbox should be more or less perfect for the 1y.
Yes the 1.9 will give you more torque - but not loads! You still end up slowing down up hills - just not as much. Fuel economy is obviously beter at low revs - but if you up that top gear you will be constantly changing down a gear when you get off the flat.
The 1y will not give you much in terms of power. It does get you a very cheap reliable engine. My 1.7d was more economical but to replac it would have cost me a fortune.