You can also buy shortened bump stops. You should be wary of cutting them because the tapered design allows for a progressive "spring" rate of the rubber itself. It's more complient at first due to the small size and ramps up from there. If you just cut the top off you'll be starting at a higher than normal bump-stop-spring-rate-whatever. The worst case scenario would be to have just a fat rubber cylinder as a bump stop that would provide no progression and earn you holes in your shock towers.

You'd have to look around for the appropriate stops, but I recall being told once that Energy Suspension makes them, along with others. Places like Hoerr or Pegasus Racing would be a good place to look.
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Justin 66 122E, 71 145S
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