Does anyone have any suggestions for products or process around re-waterproofing GoreTex? From what I can see the basic process is this:

Wash the garment by itself with a cleansing product to clear all the pores.
Hang and allow to dry.
Spray with a waterproofing agent. Allow to dry and spray again.
Either tumble dry or iron the garment to ensure a good seal on the waterproofing spray.

Has anyone had any particular success with this process? Any recommended products? Any to avoid? I've heard that washing in a waterproofing agent is a bad idea because it stops the garment being breathable.

Thanks