The coil overs breath better. I know .. what the H does that mean? *L* But thats how it feels ..
Wash board is wash board .. at low speeds. I don't think that is as smooth as stock, but with 37's what do you expect. But you run both suspensions at SPEED and that washboard will disappear. It's the bigger deflections that the Fox suspension shines in. If I hit a berm in the road, the coil-overs eat that up, and the best word I can use to describe it is it feels like the whole suspension 'undulates'.
Really hard to describe, but any ride in the country will bring a smile to your face. You'll feel that freer suspension movement, and forgiveness and for some reason my brain always flashes an image of me in a trophy truck when I feel that.
I love it, and my wife loves it. Suspensions aren't crude like they were years ago. Now when you step up and pay good bucks for that performance suspension you get what you pay for. solid parts, engineering and beautiful real world results. Not messed up suspension geometry, a squirrelly ride, and premature component wear.
I've got the coil-over spacer here, and didn't use it. I wonder if you could go hog wild and install that above the coil-over, with the 5" rear coil and small spacer for about 8.5" lift. I should email BDS about that. At first my installer thought it was required and attached the spacer, but reported he didn't think it fit on the truck, so they removed it. It is probably meant for the 4" lift. They through everything in the box, and have to sort through it all for what you need, and the directions are challenging in that way too - they interlace the 4" & 6" instructions. And the other truck they did that has the 5" rear coil did not use it either. But since the straight performance 6" coil-over kit allows 37's with NO rubbing issues then I won't ever care really. I'm a happy camper as is.