Axle ratio selection with T56

Tire size plays into it all as well. The rear wheel openings limit the available tire height without modification. With ~26" tall street tires and a 3.55 rear gear I'm chugging around 1700 rpm in 6th to do 70. When I have my street slicks on that are closer to 28" tall I'm closer to 1600 rpm at 70. All of this is with the .5 overdrive of the Viper spec trans as well. Some of the others have less overdrive like BBSwinger was talking about.

The first gear ratios on most of the aftermarket units were one thing that drove me away from them. Some were just ridiculous like 3.5:1 or worst. The split between first and second was pretty big as well. I guess it's nice for someone who doesn't want to work hard to get a car moving, but that gear would be over so fast I don't see it being useful.