The 25R is a 20A cell, perhaps the place you bought them from has got the amp limit wrong. Some places also over state the amp limit.
You're OK up to 128W with a 20A cell on a series regulated mod. If I remember right the IPV4 s is 120W. Those cells in my opinion are good for the max wattage of the mod. They're excellent cells, I've got three pairs for series mods and four for tube mechs.