Springs were easy to get, I just went through Zebra. It's like a 3 week wait since that's how long it takes for BC to get them out. Now that I've had them on for a little while, I can truly say that it is so much better. The ride is very firm obviously, but wheareas before it was incredibly harsh now it is more compliant. It's busier than the stock spring rates since they're much stiffer and you feel every little bump. I can actually hit dips and bumps now without tensing up like before. And I rub less on the same ride height, that was a big reason I did this. I had considered raising the car some to stop the rubbing, but now I can stay at this height (maxed out low w/ one rear lockring taken out). On that note, the higher spring rates will raise your car an inch or so. So you can't slam it, the lowest you'll be able to go is about tire even with fender.
And handling feels better. In smooth turns, there is no difference, but if you're in a bumpy corner, the car is much more planted. Less roll than stock BC springs on normal damping, similar to my previous maxed out setup, but the difference is that when you hit a bump, the car doesn't get skittish. Before, if I hit a bump in a corner, the suspension couldn't move since the damping was slowing everything down so the whole car would bounce around. And transitions are much better now, I can feel what the car is doing.
The 12/14 setup I have now is as high as BC goes. So I went up 4kg/mm in front and 2kg/mm in rear. I also have a stereo setup in the spare tire well that weighs more than the spare so I took that into account. It's hanging behind the rear wheels. I likely see boost in the future so that is another 80+lbs in the front so I considered that as well. And my damping is now set to 14 clicks from soft, still playing with it, but I think I like this one.