Shift Kit
 

I keep reading about shift kits for the 48RE what exactly do they do and what is the advantage to putting one in?

Basically it corrects the shortcomings of the factory valve body calibration. The valve body is set up from the factory to provide shift qualities that wont be objectionable to "soccer moms" and to handle the power of a stock engine. Shift kits increase torque capacity (due to increased line pressure) and firmer shifts. Some of the better kits allow you to slightly change shift points. Trans-go is one of the best kits in my opinion, install one, adjust the bands and change the filter. Unless you get crazy with engine mods shift kits go a long way to improving the durability of the trans.

trans go is a good upgrade from stock firm and crisp shifts not the laggggggggg like the stocker