How off will my speedometer be if I just get 4.10 gears w/ t-loc without a custom tuned computer chip? Off by a lot or a little? Just curious b/c I'm def. thinking about getting a 4.10gears and t/loc but I wanna get a chip, but don't know which one. Thanks a lot for your help. BTW I have a 2000 v6mustang with a Transgo shift kit.