How can i change the gear ratios in my car?

i have a new scion tc (manual) and i would like a transmission with different gear ratios... can i have my transmission rebuilt with different gears or would i have to just find a different transmission? or am i out of luck?How can i change the gear ratios in my car?
replace with new transmission,,transmission gear is not easy to modify, hard work and expensive to make.

best remedy is to look for new differential..much economical and easier to modify.How can i change the gear ratios in my car?
If it is automatic, no. If it is a manual shift, it can be rebuilt with new gears but they would have to be available.
What is it that you want changed in your gearset?

Do you want longer legs for cruising or do you want more acceleration?



Or do you have a big gap between 2 and 3 that you want closed or something like that?



You may only have to change the final drive ratio.



Have a look in Japanese wreckers and parts importers for ';Ipsum'; or ';Avensis'; parts.