Turbo charging a E39 BMW 528i

hello, I have tried looking all over the web about this subjuct like Bimmmerfest and other such forums, the common answer is "buy the new M5" and I would if I had the money, but I don't. Ok the car, I have a 1998 E39 BMW 528i, it was made in the sixth month, so if I am correct, I have the aluminum block and head. I am pushin close to 200 hp, and I want more. Idealy, I would like to boost it to 600hp, but that would involve too much other stuff (tranny, rear diff, ect.) so I would like to double my HP, I have the 4 speed auto and that tranny can handle over 400 hp. what would be the best way to go about this. I know how to do engine work, and had this engine apart, what is a safe preasure to push with only changing the piston rings and injectors. what would I need to do to hit 400hp, and not blow a head gasket or knock. I want to be able to run pump gas so 93 octane is the highest I can go. thanks for all the help for a turbo newb    

Talk to the guys over at Horsepower Freaks. They have lots of fun stuff for BMW!
http://www.horsepowerfreaks.com/