Sleeping bag spray on DWR

I'm a newbie and have a question about my sleeping bag. I've got a Kelty Cosmic Down 20, which doesn't have DWR from the factory, but it does have the hydrophobic DriDown. Should I use a spray on DWR, like ReviveX Durable Waterproofing? Or is that going to mess up my bag?

Thanks.

You want the spray-on water repellent, not waterproofing. Your body puts out quite a bit of moisture at night (the technical term is "insensible perspiration"), and this moisture needs to escape through the outer shell.

You can test if you really need it by using a squirt bottle with a fine spray of water. If the spray beads up on the sleeping bag shell and can be shaken off, you're OK. If it soaks in, then get the water repellent spray. Revivex is a good brand, recommended for sleeping bag shells (after laundering) by Western Mountaineering.

Thanks for the input.