Just some helpful info.
You can get better bearings installed in your Eaton Blower at Magnuson Products in Cal. I am sending mine out next week to have BETTER bearings installed in the case and the nose. I already have paid to have the rotor pack bearings switched.

Also had a custom 2# billet pulley made for the nose.... looks identical to the stock pulley!

 

does better bearings simply increase longevity or does it actually increase performance?

 

Will better bearings raise the redline for the supercharger in other words will you be able to spin it more and not be "overspsinning" it

 

well with the eaton i doubt that over spinning is really the problem, its more likely just heat generation making it more unnecessary to spin it further, but i could be wrong on that. Just thinking that the blower limit is probably lower than the efficency limit.

 

Better, tighter fitting bearings will cause the rotors not to make any noise when spun over operating RPM's. The rotor shaft is less likely to move as it does with the stock bearings because of the plastic sleeve.

 

How much, might as well do it the same time I get it ported.

 

I don't know.... mine was half done my someone local then stopped because he could not find the case bearings. I was roughly qouted around $115 to rebuild the nose and $30 per bearing case + install.
Again this is a very rough estimate!