I don't know much about Apexi stuff, are you talking about an AVC-R? I know that that can show things like injector duty which cannot be used with MFi.

The Apexi is a quite advanced boost controller, probably overkill for a standish RS Turbo. I'd recommend the Greddy Profec 2 Spec B, it is cheap and easy to work with. If all you want to do is adjust the boost while driving and have better boost stability then it is ideal.