Shimano SLX HG-81 and SRAM XG-1080 cassettes can both be used with OneUp Sprockets. Although a few additional install steps are required. See below for detailed descriptions:
In order to use the XG-1080 cassette with the OneUp sprocket you will simply remove the 14T cog rather that the 17T cog. All other steps in our standard instructions located here are the same. The only downside to using the XG-1080 is that the percentage jump between the 12T and 16T that remain is 7% higher than between the 15T and the 19T of other SRAM cassettes. You are rewarded with an incredibly light 297g converted cassette however.
Shimano SLX HG-81
The reason the SLX cassette is not readily compatible is that the 15-24T cogs are pinned together. To make this cassette compatible you simply need to remove these pins. The result will be that the 19T, 21T and 24T sprockets will be loose. Note the loose sprockets have the potential to cause more damage to aluminum free hub bodies. For peace of mind it should be noted that SRAM PG-1030 cassettes have loose cogs as high as 28T.
If you choose to continue, do so at your own risk.
Step 1: Separate the cassette segments and identify the middle cluster of 5 cogs
Step 2: Use a hack saw or other metal cutting blade to cut between the 15T and the 17T cogs. In doing so you will also cut through the plastic 2.35mm spacer. This is ok because this washer will not be needed for the OneUp conversion. If you wish to run this cassette in its 11-36 configuration later you'll just need to source a new washer from your local bike shop.
Step 3: The cluster should now separate easily as shown below.
Step 4: Assemble the OneUp Sprocket using the standard instructions located here.