:If you have a built engine with forged internals. Also money wasnt a problem. :I would buy the GT28RS and run with 30 PSI of boost. :They are a lot of Turbo for not all that much money. :If you only ever want to run 20 PSI or less then buy the GT28R.
I forgot to add get the GT28RS with the 0.64 AR. NOT the 0.85 AR. They are too big