Thanks again guys for all the help and info.

I've had a look around and found a used 2 pot rear caliper off a GC8 STI RA selling for $198 plus postage, the seller said all the bolts are there except one of them is missing an brake pad which doesn't bother me much because I will be getting a new brake pad anyways.

Through further research I've come across a few people saying a Dog-Bone Adapter is needed.

My questions if anyone can help is:

1. Is that true and if so where would I find this Dog-Bone Adapter?
2. Will this be a problem fitting it with the DBA rotor I already bought?
3. I presume workshops like S-Technik or Maximum Motorsport can help me with this changeover or upgrade?

Thanks again guys