If you have a 2003-2005 Dodge SRT4 and have over 450 wheel horsepower then this is an item that you should strongly consider.
If you have a unsprung hub, hardcore clutch that will shock the drivetrain and input shaft, your stock input shaft will be put under some pretty serious stress. Eventually, your stock input shaft can twist and or fail, and thats where this piece comes in.
This new input shaft is made to handle the abuse, and comes with a new straight cut first gear that changes your first gear ratio for a longer 1st gear.
More info here: