Look up something called "critical rotation speed" and how it relates to higher order vibrations.
Is this a manual or automatic? If automatic this will also affect the transmission itself as well as the drive line.
Regardless. Consider wisely. Maybe there IS a reason why you don't see those really low rear end gears that often. At the minimum getting the set up perfect for a noise free set is going to be.......tough.
NOTE: pay attention to the parts about what happens when the rotational speed of the drive shaft gets at or above the critical speed of the system. This might make a great "lesson's learned" thread.
>>from one of the links.
REMEMBER THIS: When a drive shaft runs at its critical speed, IT ALWAYS FAILS, and the failure is ALWAYS CATASTROPHIC.
I just ordered a 4.56 kit and am aware of the critical shimming process required on installation as well as the pinion depth and backlash.
Car is a standard 5 speed.
Also am aware the engine will be spinning about 2900rpm@65mph and fuel efficiency will go down significantly.
Will definitely need some better gripping and wider tires because i love a good 0-60.