new lifter ?

Yup. Verify lifter rotation when you first put them in dry. Then use assembly lube on the lobes anad faces. It needs to start immediately and run above 1800rpm for at least 20 minutes before you let it idle. If you have dual valve springs, the inner spring should be removed... (this is not the flat wound dampener, but a true seperate inner spring)

Do it just like it was a brand new cam. Because to the cam, it is. You have to mate the lobe with the new lifter.