nickel417

why such high a/r and small turbo? how does a ~.86 with a 66 mm sound?

Fobra

sounds pretty good to me, but like fox is saying you have to think about what your end goal is, if your going to stay with a stock block then you might want something in the .5-.7's... from what I have seen a .86 67mm would probably boost around 3200-3500 and maybe max out on 93 somewhere in the neighborhood of 650 rwhp - depends on head work/internals all that stuff... and on what your looking for... if your staying with a stock block you might want to stick to the .6-.7s

FoxGT

Trim is where you want to make your mind up on. On the compressor trim plays a MAJOR roll in where your efficiency is. A/r on the compressor side does very little, It helps gain a little efficiency depending on your desired pressure ratio. It is the opposite on the turbine side, the trim will have a very wide range of application, whereas a/r plays a major role. This is why you will hear a T3 or T4 exhaust trim used on anything from a small 4 cylinder to a decent sized v8, but they will have a vast difference in a/r (bigger a/r for bigger engines, smaller for smaller engines), but for compressor side you'll hear alot about different trims, but very little about a/r (some companies don't even put the a/r on their compressor housings).

If the inlet on the compressor side was flipped & the charged air came out of the center, then yes a/r would have a big role.
VGT's are sized very large because they do away with the wastegate, obviously when you're at 6000rpm you want the exhaust housing to act very huge so that it only delivers say... 12psi. If you're going up in the rpm range, the vanes will constantly be moving so it's hard to compare it to a certain trim turbo. It would be different if it had the vanes open to x amount at this rpm, then x amount at 1000 higher rpm. But it is a constant variation based on how much pressure it's producing. If pressure drops below 12psi, the vanes will open more, if it raises above 12psi the vanes will close more. But like I said, you're talking about turbo's designed for low heat ranges that weren't designed to operate at the temps gasoline engines see, so be prepared for destruction. Honestly i toyed with the vacuum controlled before, now i'm trying with the electronic controlled, but I have my hands full with work & other people's cars, I get little time to work on my own.

Fobra

Well it is just a thought, in all likely hood im just going to go with a good single BB