The top out spring is the little coil at the top of the shaft below number 54.
xy9ine's instructions are for an air fork. With a coil, you need to get a shorter spring too. The 160mm spring for the 55 is at least available since that was the stock length last year.
Yep. You shorten travel by getting a longer negative spring, or just adding appropriate length spacer. PVC will work. With a coil spring fork, you need to reduce the length of the positive coil the same amount you add to the negative side. A spring is a spring, regardless of manufacturer. If it fit in the leg, and is the right length and rate, it will work. I love frankenstein forks….
With an air fork, you don't have to worry about the shorter spring.