ooops my bad, the internally gated one is the Gt3271. The Gt3571 is free floating.
http://www.turbobygarrett.com/turbob...1_452203_1.htm
Is the Gt3271.
A pair of those babies will do you well, and save you some hassle with the internal gates. They cost $880-1000 pending on where you go and there is 3 turbine housings availible. 0.78,0.69 internal, or 0.78 free floating.
Here is the plot on the turbocalculator:
http://www.not2fast.com/turbo/glossa...orDutyCycle=85
You have to click on Gt32 on the map scroll bar. but it will allow you to check it on various compressor maps. For street use you'd like too have the maxiumum compressor effciency occur around the torque peak. which pending on cam selection (stay mild with reverse split) will happen with these.
Have fun!