Question about different gears
 

I dont know much about different gear ratios and would really like to know more about it! What differens does it make to put a , for example, 3,55 on a stock gt, compared to a 4,10 on the same car? and what KIND of differenes? As far as I have understand, the more mods you got on your car, the higher gear-ratio you need. Is that right? :helpsmili