You need to make sure the car hooks up on the starting line because that is where a lot of the time is lost. Slicks would be the first thing then I would go 3.91 gear ratio.
he is talking driveability and you can see that with the 3.55 and 26" tire. if he was going to do a gear change he needs to figure out what rpm he can live with and then figure out what tires will fit.
