Changing Lens.

[yammaster]

I have the Git2P 90. I want to replace current lens with best 90 all glass lens made. Current lens has debris right dead center behind lens. Anyway, I've watched some videos on replacing lens. Looks like just take off front, remove glue holding lens, remove two screws, replace, correct?
Anybody done this, and which is the best lens?

 

[tmvideo]

Here is tutorial:

There are some 90 lens at GitUp site: http://www.gitup.com/16-lens
But @gitup have to recommend which one is better for Git2P.