the S2's match up more with the 272 Kelfords.

the 280 kelford have a split duration 280 intake and 276 exhaust and also less lift on exhaust.this will more the rpm range even more to the right,which most applications don't need.

the S2's and the 272 Kelfords are pretty close overall,but yes the S2's are probably a little better overall and more well rounded.

you could order the 280/280 Kelford setup would be nice and probably make more power than the S2's in the same range of rpm,but then again the GSC S3's again would top the 280/280 Kelfords imo.