The problem with the AGXs is that the shock body is not any shorter then the stock shocks. So you will be riding on bumpstops if you mega-slam it. Then again, if all you are doing is drifting it, then it wouldn't matter. In fact, it might be easier to get the rear end out if you're already sitting on the bumpstops static.
Regarding the D2 (which are chinese-made, not U.K), Omnis, Stance,ect....
There are various taiwanese/chinese manufactured coilover nowadays. Their packaging and marketing is great . The manufacturing quality is pretty good too (well...). Their performance, on the other hand..............Most people will not notice the performance difference cause they drive on the street and just looking for a slammed look, great for drifters cause you get the "look", but that's about it. You get what you pay for.
Just do a search on google and read for yourself.