These Power Line knuckles for the T/E-Maxx are a direct replacement to the stock plastic knuckles.

These aluminum knuckles are stronger than plastic which could be a good or bad thing.  The strength is good, but the hardness could transfer impact shock to other parts like steering turnbuckles/tie-rods. 

These parts do not improve performance. 

The Power Line knuckles have a problem maintaining the position of the ball-joint retainer.  Even using a thread lock material, it's possible the retainer will work its way loose. 

The inexpensive cost of these may make it worth the effort to keep the retainer in position. 

The bearing slots are a perfect fit.

All things considered, they are not a bad purchase at all