To turbo charge a non-turbo charged engine is very invovled, as not only do you have to change a lot of parts, you also have to lower the internal compression ratio of the engine to cope with the forced induction pressures. As mentioned, by the time you strip the current engine out and down you may as well source a replacement TFSI engine to replace it with, but again getting one with all ancillaries, wiring and ECU and then factoring any brake and suspension upgrades required for the power increase will cost so much that you may just be better off going down the GTI route.