yeah - everybody making the same mistake for the same reason. i see a lot of that. i don't know anybody actually doing the math before doing their setup. most people run "what that guy ran", and go entirely on recommendations, without considering the physics and math involved.
that being said, it all depends on the track. for example, you would not run the same final drive ratio for a track with long straights as you would for a tight technical one. we used to change gear sets all the time, ranging from a 3.91 all the way to a 4.86, depending on the track and the competition. we usually ended up running a lower gear ratio, and giving up some top speed, in order to gain acceleration. we almost never could hit top speed anyway, so having a gear that could reach it was a complete waste.
running a smaller outside diameter tire, and one that is lighter, coupled with a lighter wheel, generally gains about 2-3 tenths of a second on a 1 minute lap. there will be weird tracks, where you get caught in between gears in a particular turn, but as a rule, that's what the physics do for you.
94 Midnight Metallic Blue Cab Porsche 968 w/deviating cashmere/black interior and WAY too many mods to list - thanks to eric for creating
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"It isn't nearly as expensive to do it right as it is to do it wrong."