Do your research and start out simple, don't go BIG right from the get go. Its good to learn first on a mild setup to familiarize yourself of a turbo car.
I was running 12 psi on my stock 4G64 in my 7g for a good 6 months and had no problems at all. The car pulled hard on highways and was fun to drive.
You should be able to use the stock Evo 8 manifold and turbo on the 8g 4G64's..they should bolt right up. Then you would have to fabricate the rest of the I/C piping and exhaust. Unless you get a kit that is 8g Galant specific then you are good to go...its just a matter if you are willing to tackle the install yourself or spend the extra cash and let a shop do it for you.
Good Luck.