Will a Precision 5557B 0.82 A/R Exhaust housing fit on a GT3076R that has a 0.63 housing vise versa?

I have a buddy with a GT30 and the 0.63 and he wants a 0.82 while I have a Precision 5557B with a 0.82 and want a 0.63 haha. They are both 3" V-band

 

No. Exhaust wheels are completely different, and are not interchangeable. GT -R turbos use specific housings.

 

Hmm okay fair enough.
I have a D16 turbo making 160whp and am shooting for 250whp next summer..
Will the 0.82 exhaust housing give me more LAG or whats it going to do for me?

Compressor Wheel: 74.9mm Exducer; 55mm Inducer 54trim
Turbine Wheel: 65mm Inducer; 56.6mm Exducer 76trim

 

Yes

 

In your case (as said above), yes. The power does shift higher to the upper rpm band causing a bit less responsiveness. Stick to a .63A/R or even a .48A/R for those particular goals.