compression with 274cam
Comp says a dual from there listings but they have the new conical springs that are very good, I just put a set on a sbc with a much larger cam then the XE284 they 145 on the seat and 340 open. Very nice springs, they are the new tech. but they are a bit more in cost.
They also don't fatigue like a std dual spring or single. They are better from harmonics stand point also at high rpm's.