Nikwax TX-Direct, either spray-on or wash-in works well, as does Revivex's product (can't remember what it's called.) The Revivex stuff left some temporary white marks on a Gore-Tex jacket of mine once, but maybe I over-applied it or something.

Most of the lightweight nylons these days seem to have a DWR finish from the factory...does water bead up on it?

Did you use the Momentum 90 from Thru-hiker? If so, give us a full report. I've been thinking of buying some, but at twice the price of the 1.1oz ripstop, I need encouragement.

Also, what pattern did you use?