Please update me if things have changed, cause this is about community knowledge sharing,
CT2x housings sell for around $200 or more.
GCG as well as many other turbo shops will upgrade the ct2x core and bore out the housing for anywhere between $700-$1500+
$700 mark is a journal bearing inducer side only - $1500 ball bearing wheel / exducer side mods. Spent $1,700.
Or... You can try buying an eBay core $200-$700. Arrives with a damaged wheel because of international freight. The seller only will replace if you return registered post, but the cost is as much as the item and they will only send in the same packaging to arrive damaged again (or they are cheaply made). Wasted money. Spent too much nothing to show.
Or... Turbo suppliers like Falcon Creations (from twisted motion) sell an upgraded ct2x series with upgraded 16g wheel for about $800 or less delivered. Spent $800
None of the above mods will perform like the actual gtx3071r referred to. Ct2x housing has an ar of .3x-.4x compare to .6x housing of a gt3071r, not to mention other aspects.
Upgrade the ct2x turbo has always been a goal, to show my age, I have had back in the day the original t04e upgrade by GCG (in Sydney, if we are referring to the same shop). Journal bearings don't last, try a rebuild but not within spec/doesn't last.
I have recently thrown away two ct2x housings, given one away to a forum member. Over time wasted a lot of money to learn about turbos. I still have a ceramic coated, ported, ct2x housing sitting on the shelf to remind me never try re-coring a ct2x ~ causse it's not cost effective to get a core/modidpfy vs outcomes/products in comparison, unless someone knows something more...