The overheating problem is a known problem with these cars. About removing the thermostat. That is not a very good idea, it will take longer for you engine to warm up and when it is really cold it won't have the chance to warm up. which keeps the oil on a low temperature, end that results in a bigger turbo lag and bigger internal wear.
The only thing that works is a new radiator. Prefferably a copper one. It helped me big time. I never have a problem now with the temperature, even at 30 degrees celcius and WOT for 15 min.
I did a search for some pictures of how the cooling should be connected. But i think when you look for 5gtt on google you will find enough pictures, and when you combinate all you will figure out how it works.
Have you checked your cooling system for air? That contributes a lot to a worse cooling.
Derby