Low gear set from A999 installed into 904. Anyone experience gear noise?

Hey All. Like the title says. I pulled a low gear set from an A999 and gave it to my local builder to install into my 904 during a rebuild. I had read that the low gear set can be "noisy". Yes it is noisy. Odd thing is that it didn't start until I had a couple hundred miles on it. Has anyone experienced this and can you describe the sound for me? TIA.