Foggy brownish tint? I swear some of you make stuff up for giggles. I have four (yes four) v.5 PO42's and not one has a foggy crystal with a brownish tint. All are blue, like the earlier gen PO42's, and all are perfectly clear. I have never so much as seen a photo of one with a foggy brownish tinted crystal.
Seriously, the only mods I'd do to a v.5 are the gen crown and tube (if it needs it, like one of mine) and relume the hands, pearl and markers. Anything else is just buggering about with money I would put towards a gen.