I have the Gnarly & Q-stealth combo on my 250EXC. I like it. I had a 250SX with a Gnarly & Powercore2. I didn't like the Powercore2 as it was too noisy for my liking. If I kept it, I would have put a Q-stealth on it as well. My interest in the Gnarly was for durability in the scrub, but these days I'm pretty good at keeping my pipe clear of obstacles so I will likely leave the stock pipe on my 200EXC.
It's not 100% necessary to completely dry the filter. I haven't done so in 3yrs. I have found that if reapplying oil to a moist filter (after a good squeeze), it's easier to spread the oil around and penetrate the foam.