For those WR owners considering changing rear shock springs, but aren't convinced I just experienced a ride-changing experience on the weekend, which will hopefully help someone here. I'd had the suspension re-valved on my old 426 and noticed it was a massive difference. At the time the tuner said I should probably go with a different spring, but stupidly I decided to just stick with the re-valve, which made a massive difference on it's own. I've gone about it a different way with my new 08 WR450. Apart from clicker changes, the only change I've made is to change to the correct spring for my weight based on race/static sag measurements. I went from a 5.5kg to a 5.1kg spring to come with the correct measurements and the difference is just a big as when I had the full re-valve done on the 426. And it's not just on rough, choppy stuff, where it is a dream now by the way. I was sort of expecting a big improvement there, but it's also improved things on flat ground (unless I'm just that happy with how it's now handling that it's all in my head!) On the flat it appears to have a heap more grip now, to the point where it even monos heaps easier. It now seems to squat and drive where as before I was getting a lot more wheelspin. Best $150 I've spent on the bike by a mile. If you're considering it, don't hesitate. I knocked about 15 seconds off a 12 minute enduro loop that I train on. Awesome stuff.