I own a 2009 mustang shelby gt 500 which i have modified to 650HP. My question is: i want to replace the stock differential with a more agressive differential. Can I go as high as a 4.10:1? or will it not drive well?

 

do you mean replacing the gears? Or the whole differential itself?

from your question it seems like you want to replace just the gears, and I'm sure you can search the shelby section for a thread about somebody putting in 4.10's

good luck, and sweet car

 

What's the differece between replacing only the ring and pinion gear and replaceing the whole differential?

 

well the ring and pinion sit inside the diff, so you're only replacing that small piece.

also a gear set will run you cheap money compared to replacing the entire diff. And with those power levels, im almost certain the stock diff is perfectly fine.

on a side note, what have you done to the shelby to get 650hp?

 

man, 650hp & 4.10's...you're gonna need one serious tire to hook..LOL. I'm at around 612hp at the crank with 3.31's and I've been think about going to 3.73's, but worry that might be alittle too much....

good luck with your decision

 

Yeah, a 345+ wide tire would be a minimum and still come short of grabbing, lol.
Then again, you don't have to build those cars for drag racing only.