I’m looking to replace my current 4.1 diff, as it’s on its way out, and I’d like to go with a lower ratio for better motorway cruising without turning the car into a slug. I was considering a 3.9 paired with my existing 5-speed, but I’ve also seen people mention that running a 6-speed with a 3.6 is effectively the same as a 5-speed with a 4.1, just with an overdrive 6th gear for motorway driving.
Has anyone had experience with either setup, and is the 6-speed/3.6 combo really comparable to a 5-speed 4.1 with an “extra” overdrive gear?
For context: it’s a Mk1 with the 1.8 VVT and the standard 5-speed 4.1.