I have just the same manifoil for my rb25, but I havent tried it yet.
One thing I was worred about when I saw it, is that the wg pipe sits in the mid of the collector.
The exhaust must turn 180 degrees to reach the wg = bad flow.
Think I will cut the whole manifoil up in peaces and make a new one.
Edit: now I had to go home and take a look at my manifoil. Luckily I only had to slot out 2 holes a bit to get it on.
The turbo wont fit at all though so I am going to cut it all apart.
Holset HX40 is a beast!