Yes they do a good job at reducing resonance.

Quote Originally Posted by JAZZCNC View Post
Also be aware that a lot of company's supply the pulleys with a small pilot bore which you then bore to the size required. Drilling with a decent drill press is possible but very easy to get wrong and create runout and if done this way then I'd recommend drilling smaller and reaming to exact size. . . Job best done on a lathe.
Get them delivered to me and I'll bore (or ream) them to the right size on my lathe for you. Just pay me the postage...it's only a 5 minute job, if that.