Thread: Correct valve stem seals?

I am under the impression that to safely run an XP cam on "stock" heads you need modified retainers, and Vitan valve stem seals. Is this correct?
Also I ordered a complete engine gasket set from Fel-pro and it came with some "Premium valve stem seals"... I have done as much reading about this subject as I could find, and am still unclear if I have the correct valve stem seals or not?

I kind of figured they are, but I am puzzled as to how using these provides .020 more lift... I sat one of these right next to the old stock one and they look identical in size and shape, just different color.

I have 105# springs and modified titanium retainers. Just need to know if the valve guide seals I got are the same ones ZZP talks about getting extra clearance from, or if I have to order there's specifically

I may be mistaken but the Viton valve seals and fel pro are different.