The higher the ratio in the differential means the longer the gears and going a certain speed will pull a lower rpm vs a lower ratio differential. So basically what I'm saying is a 2.95:1 ring and pinion in your diff will pull lower rpm's at a certain mph rather than a 4.10:1 and also the gears will be longer. I understand that transmission gearing plays a role but I think in most cases I would be correct. And also turbo cars benefit from the longer gears so it is a win win.