If I install 4.11s in my car, will I need another re-program? Also, I have 3.42s right now-how much different will my gas mileage be, and performance gain (I have a M6).

 

I swapped my 3.42's out for 3.73 and I saw a tremendous performance increase... now my buddy just replaced his 3.42's to 4.11's on a supercharged M-6 and he can't seem to keep his tires from spinng everytime he takes off in less than 3rd gear. Now as far as re-programming.. all you have to do is your speed-o so it reads right again.. you can do this with a hyper-tech pwr programmer or you can take it to a dealer or somthing of that nature. As far as gas mileage.. mine dropped a bit but with the performance I got out of it I don't mind one bit!