If you have a 1.8 in your car right now all you´d need to buy is an ECU, (new injectors for better fuel delivery wouldn´t help either), then you can find an intercooler off an old Chrysler Conquest (I think that´s the name of the car) in the junk yards, and then you´d need to get the GTX header and the IHI turbo. I know corksport has the header for $180 US and they say if you want they can find you a turbo too. Even with all that I´m sure it´d be cheaper than swapping with a GTX.
The only difference between the GTX (BPT) and the BP is that the GTX has an 8.5:1 compression ratio as opposed to the BPs´ 9.0:1. ;-)