I haven't done this myself but as an owner of the exact same car I have considered it and done some research into it.

For the time and effort i'm sure you realise that it really isn't worth it as the 1.8 as standard puts out 112bhp. Let's say you are aiming for around a 50bhp or more power gain. Well as ST170 will provide that perfectly and in N/A form. You can pick them up for £1500 and use the money from selling yours to go towards it. It runs 170bhp from the factory and with simple bolt on mods and a remap can be good for 200bhp. So that's nearly 2x as much as your 1.8 - something not realistically achievable by a simple low pressure t/c.

However i'm sure you have been told this many times and as such I will give you three bits of advice.

1. Buy a good quality pre-made t/c manifold so you don;t have to make one. There are loads out there just don't buy a cheap one off eBay that will send shards into your turbo.

2. Watch the MCM turbo conversion vid. Much of it applies to any t/c and is very in depth and descriptive.

3. Don't think to yourself that this will cost less that £1500+...

:L