Do i even bother using them, i am already deep into porting the heads and they will be used on a turbo charged motor. From what ive read they stop making power after 4000 but with a good port and forced air will that matter?
iv'e ported a se of e6 heads before and with a e303 cam it pulled really hard from 2500 to 5000 rpm almost nothing at 6000. i later ported a set of 289 heads and put them on. the first tim i got on it i thought i had killed the engine with the heads till about 4000rpm and then it just woke up and went til i hit the rev limiter at 6250. i lost alot of low end torque between 1000 and 3500 rpm. the e6 heads make really nice midrange and low end, but not much good past 5500 IMO