Thats a pretty big turbing housing.
<div class='quotetop'>QUOTE</div><div class='quotemain'>A/R Explanation
A/R is the rated volumetric efficiency of a turbos 2 sections, so to speak. Imagine if you have a garden hose spraying water out at a pinwheel
with the hose open ended, the pinwheel spins okay. Put a nozzle on it an the pinwheel will spin like mad.
There are issues with the nozzle on the end, you lose volume but gain pressure. With the nozzle off you gain volume, but lose pressure and you can't turn the pinwheel as much.
Simply put, on small displacement engines a smaller A/R is better, on large displacement engine a larger A/R is better due to exhaust volume.
A larger A/R will spool later and provide a higher power band, if your engine is capable of reaching the RPMS it should be used in.
You can't cross compare different types of housings and wheels, but if you have a typical T3/TO4E 57 trim with a stage 3 exhaust wheel and a .48 A/R housing, it might have a powerband of 3000-7000, with the .63 it might be 4000-8000, and with a .82 A/R housing it might be 5000-9000. If you have headwork and cams that stop pulling at 8000 RPM's, it's smart to run the .63 A/R housing. If you have a fully ported head and huge cams that will make power till 9000, the .82 A/R housing would be a better choice.
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http://www.turbominivan.com/tech/arratio.jpg
http://www.supracentral.com/articleimages/arhousing.jpg
http://www.supracentral.com/articleimages/basics_trim_turbine_formula2.gif
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Would be a descent turbo for a v6 depending on boost level. Not sure how efficient it would be, I could figure it out at different boost levels, but I am too lazy to do math.