Originally Posted by slappy

SO....
What are the possible downsides of throwing 4:10's in an 04 GT besides a slight loss of fuel economy?

I know this will void the crap out of my warranty, im tempted to see if i can sell my warranty back to ford, or i could just keep quiet about it.

so why would this void the warranty? what is this going to wear down and break prematurly?

I totally want to give my car a little kick in the seat of the pants, this looks like the best way to do it.