The '07 shock was almost certainly valved differently than the '06, but only a shim or two here and there. It's not uncommon to see two bikes made the same year with slightly different valving. The bolded shims are shims that were changed from the stock size. Occasionally there is one added. I weigh 170, so it's not so different. The symptoms in your rebound as you describe them are classic YZ/KYB complaints. This shock setup originated with Dave Johnson of SMART Performance in almost this exact form. I've only made minor changes. I was getting rear end kick to the extent that the bike of the bike was moving around a lot, and the tail high attitude on hitting the next successive whoop was causing the front to be unsettled and squirrely at speed. This shock addressed that completely. The HSC modification came later to make the rear more compliant among big rocks in 1st and 2nd gear. Originally, I could sit the bike on the ground, bounce the seat with my hand, and it would rebound a bit beyond its static height and then settle back. The fender used to wiggle up and down freely while it rode down the freeway in the truck. No more. Now it takes a full second or so to rise from the same seat bounce, and doesn't float over at all. I found it really hard to believe, just on the surface, that that much stiffening of the face stack would not cause packing, but the thing is that with the stock setup, any time you get the rebound just about right, most of your damping is being done by the adjuster needle, which is a fixed orifice once you set it. With a stiffer valve stack, the bleed through the adjuster is greater, and more of the damping control lies with the stack, which does the job much better. If I hit a series of whoops, the bike does actually squat just a little bit, but it stays down, and stays behind me, and the front doesn't twist into the next one, it just tracks straight. Running through a string of whoops in the desert, I never feel like the rear end "packs", that is, the compression never suffers from the slower rebound or the "squat". Since you are 20 pounds lighter, you might try using 0.30 shims in only the first 6 positions off the piston instead of the first 7.