Depends on what you feel is nice. My 3.91 gear car I coast the sub at 20-25 mph in 2nd gear when the engine is cold cause the 3.91's just seem to lug the engine..once warm I do 3rd at 1,200 rpm in the sub.
Yes 75 mph can get old fast and if the exhaust is loud, forget it. Yet at 55 mph the 3.91's feel "just right" IMO
MPG is what's going to hurt the most. My 340 feels happy doing 3 to 4 grand on the freeways but gas mileage stinks.
In the old days , these hot rod cars with 4.10 gears got better MPG in the city vs the freeway. Checkout the 1970 car mags test results, I've seen numbers of 12-14 in the city and 9 - 11 on the freeways..I had to look twice and first thought it was a mistake but then reading comments in 1970 Motor Trend 440 6 pack road test "90 to 110 mph is quicker / safer with the 4.10 gear vs 3.55's" it all made sense. People used to drive 80 mph plus on the few freeways they had back then, 4.10 gear cars came with forged cranks-pistons for a reason, so they live a long happy life..which was 75,000 miles back then, lol
