I agree with Imyers.
That being said, you can add a Thule or Yakima system to most every car with or without the factory roof rails. If the car has no rack of any sort on top, there are little feet that attach to the Thule/Yakima racks that clamp inside the top of the door frame. You don't have to have the roof rack rails from the factory, though they are convenient and possibly more secure? I never had problems with their racks on the Honda's I owned when I was younger, for example, that had no roof rack from the factory.
In my observation, Thule racks seem to sit slightly lower on the car (which I like), though their mounting system has several small parts to assemble to get it to mount to your car.
Yakima racks seem to be engineered so everything lives together/one piece (less small pieces to lose if you're like me and take the rack on and off), but it sits a couple of inches higher. Simpler/less fussy to work with in my opinion.
My girlfriend and I each own Subaru's. I have Thule cross bars. She has Yakima cross bars. This is where I've seen this. shrug.
As far as the actual device to carry the kayaks, I have Yakima Big Stack (got a deal on it), though I really prefer something more like Thule's 830 The Stacker:
Thule*-*830 The Stacker
The main reason I like the Thule version is it's hollow, and on the older one like this it was a great place to shove paddles on the drive there (strap them down of course). Haven't used this one I put a link to, though I'd guess it would still be a place to shove paddles for the drive.