Need more info on a ems piggyback or full standalone Options

[mk7celica]

Ok I still dont under stand everything about a ems. 1st of all its a 2nd gen 3sgte ina gt. Well I want a bigger turbo and injectors an made a post for info on it and everyone says I need somthing to control the air fuel ect meaning a ems. So I wanted a safc2 since it was cheap and was told its not what I need and It messes with timeing and other things. So I was told get a ems. These are the 3 choices I have ats rom tuned with a ct27, some type of full stand alone<very expensive> and a piggy back. The piggy back I am looking at is the greddy emanage which is $400 and a emanage ultimate which is $650 and seems to have a lot of things it can do. But is a emanage piggyback going to do the same a the safc would do and mess with my timing and not do what I need it to do with a bigger turbo and injectors? Can I control one of those ems turbo kits for 1800 with a emanage setup? Cause I dont think a ct27 is enough for what I want