E6 have larger chambers (68cc) and bit smaller valves, the large chamber will make you loose compression unless they are shaved. Some people do use ported E6s but i tink E7s are a better choice.
On the other hand why not get GT40 "P" or GT40 Cobra heads..still a better choice.
On the other hand why not get GT40 "P" or GT40 Cobra heads..still a better choice.