The tabs on the clamps are easily removed.. i did this for the 12" KST Outlaws I'm running while I wait for my 14" Monkeys...
You just break them off with a pair of pliers.
One more thing for the 15's... the risers are 1.25"... so there is no neck-down needed or wanted. You can run full 1.25" bars... or you can get a 1" riser clamp to run the older style neck-down style for about $60... FYI