Did it make this noise before you installed the new rest? If not, I would check everything over. Make sure it's all tight. Also, how old is your string? If it's old and dry, it's going to make more noise. Replace it.

I guess what I'm saying is this. If the bow WAS quiet, and now it isn't, don't just slap something on there designed to quiet it down. Something is wrong somewhere, find it and fix it.