now thats a fun question!!
I thought since you can get a journal bearing of most turbos you would be able to get that, but checking with garrett it seems you cant.
The reason being is that they are selling the T series turbos fine, the closest one to that is the T04R which is Â£650, you can get a gt35r for Â£950 but id always be worried about cooking the bearings in them.
Do you have any porting as that will effect how much power you get and spool time, as if your porting is decent you could go to a gt4088, have similar spool and make more power.
Ed is pretty good when it comes to masterpower turbos and greddy turbos and i know a fair bit about borg warner.
does a brand bother you at all or you just after the best bang for your buck as such