Can anyone tell me how to find out a modified cylinder from viti or srp?

I’m not talking about the factory tm finishing preparato. I’m talking about companies like viti, srp …

Are you looking to purchase one, or looking to verify whether a particular cylinder has been prepared by SRP (for instance)?

If the latter, there may be some type of marking(s) on the cylinder that would suggest a builder has done their magic to it.

I want to know if it is really modified or just a sticker

Easiest way to verify would be to look for any stamps/etchings/markings and call the engine builder to see if they have record of having modified that particular piece.