Superformance is a very odd powder. It only works for certain cartridges but works amazingly in those cartridges. I don't know if it's suitable for the 6.5x55 and if there isn't data for it, maybe it isn't. It could also be that Hodgdon just never tested that powder in that cartridge. I would imagine it should work since Superformance is used in .243 and .30-06 which can use powders in the same range as 6.5x55 so perhaps Hodgdon just never tested. If there's no published data though, I'd find something else.
Maybe there's data in the Hornady load manual? Hodgdon supplies the powder to Hornady though from one of the manufacturers they contract with (Hodgdon doesn't actually make much powder themselves) so it would make sense that if the data was available, it would be on the Hodgdon data site.
For the record not all Superformance ammo (and Leverevolution for that matter) use the retail powder of the same name. Factory ammo is loaded with whatever suitable bulk powder they have on hand usually. Some of the Superformance factory loads probably use Superformance powder but it's a guarantee that not all of them do.
