Hi, I've decided and been recommended to use a Precision 7175. I had a mate that worked at a turbo joint that could get me a turbo but he doesn't work there anymore so I've been looking myself from America. There are 3 types of 7175; - t4 flange non ball bearing 1600 - t4 flange ball bearing 2600 - gt42 Style ball bearing 3100 What's the difference between them? and is ball bearing really worth it in this situation?