Props to Vector Motorsports and their Powercal cable or, as it used to be known, the flash express. Two years after purchase and they update my files, no questions asked. Steve at Vector was more than patient in helping me get the right files and getting my new laptop up to speed. IMO they are getting G8 tuning down to a fine art and as far as I can tell, the shift points are right on. Unfortunately the weather has gone south so I haven't got to "test" it out as much as I like. My butt dyno sure notices a difference.
On the 3.27 gears, I can tell quite a difference in the car. I was almost afraid to get them after reading some posts on the subject about how some people couldn't tell a difference. Not so in my case. The car "feels " lighter as many have claimed and acceleration is way more drastic. When you punch it going down the highway, 100 mph comes so quick it's going to be hard not to get a ticket in it. I can only imagine how much harder it would launch had I gone with 3.45's.
To me, it all depends on what your after. I'm trying to make mine fun to drive, while keeping it as a refined daily driver which makes some long trips from time to time. I went from 1700 rpm at 70 mph to around 2000 rpm at the same speed. If your all about pulling some g's and don't mind the gas mileage, by all means go 3.45's. That or get a 5.0 Mustang