I pulled out of ford after they put mine in (3.73s)....laid her to the floor I couldn't wait to see what they could do!!!! woohoo
There was a whine....my plastic speedo gear winding up (2.73 speedo gear) and speedometer was reading well over 100mph
only doing 60mph.
Like the other guys said...take it easy at the very first to make sure they are set right ....then driver her like a rental.....well maybe not THAT HARD. haha
I have had the gears for almost two years and NOT A SINGLE PROBLEM after laying into it moments after install.