I have emailed them previously about the housing, here is a cut n paste from the question i asked and the reply i got:
Question:
I am thinking about getting one of these, on the bottom it says that it is available with an RB25DET exhaust housing, was wondering if it is also available with a VG30 (OP6) single turbo exhaust housing, from what i know its the same as the RB25 but is a .8 not .6, if it is how much would it be, if not how much minus the exhaust housing but to suit an rb25 exhaust housing.
Im basically looking for that turbo with the bigger .8 exhaust housing, internal gate and straight bolt on without the need to have a custom dump pipe made.
Answer:
We now use a new casting specially made that is better than the vg30. it is rated at .7 a/r which I understood to be more than the VG30. It has the 6 bolt dump pattern and t3 flange.