What in considered an optimum ratio for the best compromise between acceleration and economy/speed?

Depending on the motor used as well I am guessing?

i use a 3.7 with a 3 litre engine, it feels just a little too tall, i dont like doing 10 million rpm down the highway so i prefer a tall geared car though, i'd like a 3.9, whcih would feel about right, but it depends on your driving habits i guess, do you do alot of highway driving?

Im getting feed back that genrally 3.9-4.1 is the way to go.

As for highway driving in the Z, im not sure as yet. I havent seen it do any driving

Thanks

using a 4.1 is more for a car that would be used as an acceleration machine, 4.1's generally rev pretty high on the free way, lots of noise and more fuel consumption/engine wear. if your starting from scratch its better to play it safe, try a 3.9 first.

i went from a stock 3.7 to a 3.9 and it only had like 200rpm differance at 100kph, so id say a 4.1 would be around a 500-600rpm differance, which would be considerable, so it would be reving at around the 3500rpm mark on the freeway, thats just a guess, this is pretty high for L series or any 6 series motor.. but if your not going to be doing much freeway driving, it doesn't really matter, up to you, the loudness on the freeway is more a drowning noise at that stable RPM level, and is bearable, its really up to you, i think when you go a 4.1 you won't wanna go back, but with big HP, it will spin to much with a 4.1 compared to a 3.9

If you are going turbo id recomend a 3.7-3.9 ratio, as it give the turbo a bit more time to spool, but its up to you, when you think about it, most jap cars, come out with a 4.1