Forester sti

As above!
I am looking to either convert om own AP Suretrac (OEM on MY06 JDM Forester sti) to a locking diff,
I swapped my Foz sti 6 speed gearbox for a JDM Hawk sti 6 speed DCCD but still using my original rear diff which is designed to get grip and traction through a technical setup of cams and other fancy stuff, BUT I just want that when I throw the car into a corner and floor it that the rear diff locks and spins the back wheels equally!
I am hoping someone has a 3.9:1 (JDM) rear diff that locks under power (is that what a plated diff does?? like type R's and Spec C's) and would like a more planted grippier rear end, and would like to swap??
Or any advice would be welcome,
To be clear, My aim is to go sideways!! for drift days and stuff! (pic and video below)
I have done everything else I can to help that, so this is the last thing to do!
I appreciate any help or advice on this lads!

Thanks

Dan

http://s1209.photobucket.com/albums/...IDEO0005-0.mp4