I switched from fully ported eddys to w-2s on a 421cu in,went from 10.70s to 10.50s.This was a batten w-2 made rectangular port real nice head,bought used already ported, was told they flow 305cfm at .600 never had them checked.Not impressed with that set up.So I then switched to 360-1 245cnc heads and went to a 9.97.This was a little less compression because the indys had a larger camber then the battens.This all was on the same shortblock with the same cam.