One of the biggest mistakes that has been made is after setting the spring in the desired holes, not preloading it by twisting it up and setting the ramps on the slide pads during assembly. Doesn't matter where you set the spring if its not preloaded, it will feel like nothing. With that said and assuming you have instead one of those bad springs, yes just get one for the 16 or 17. On the rollers or sliders, the factory puts rollers in...they are round. The sliders work the same but not round, they slide in the tracks instead. The reality is the rollers don't always roll because well...they can't with both sides being stationary but the sliders doo let the cam plate cone out a bit more on the bottom giving you a hair lower starting ratio and move a bit farther up on the top end giving you a hair more speed. The weight..well that's a matter of need in fine-tuning. If you do a lot of low-end hill climbs maybe the 24s would help you..just know it raises engine RPM to get the same force out of it.