if for ST165:
1. (big upgrade) 935 motorsports offers a complete turbo upgrade.
2. (medium upgrade) The MKIII Supra CT26 is a good match with upgraded comp. to 46 or 50 trim (T04E family)
if for ST185:
1. (big upgrade) ATS Racing offers and modifies the Greddy TD-06 , it's water and oil cooled, with external w/g (
http://www.atsracing.net)
2. (medium upgrade) ATS Racing offers an upgraded CT26, dubbed the "CT27" for now.
3. Custom t3/t4
4. Go with that TD05 you are talking about.. That's an awesome turbo that people in the US, usually don't go for on the 3S-GTE
Hope this helps.. (there are more options.. these are just my recommendations)
Best Regards,