i'll be running mine on the 9th of aug, i will do a thread on it..
what i can tell you as someone who went from ported
4v's to out of the box 3v's on the same motor in the same car is that the car is a lot more smoother to drive, the power comes on a lot more smoother and not as aggresive, and the engine run's a lot cleaner, and the power throughout the rpm range is awesome..
as hard is it is for me to say, because i love
4v heads, i will personally never fit another set to a engine againe..
while i have no doubt that the old
4v's match my 3v's as far as peak power goes, the
4v's had to run 38* total timing and run on a higher octane fuel
while my 3v's made over 480rwhp with 24* total and running crappy avgas
i have no doubt with some tunning, more timing, and a better carb the rwhp will go around the 540mark..
anyway thats my personal experiance with it, i'm not waving a CHI flag just telling my personal experiances with the 2 heads in question...
oh and i have a set of
4v's you can buy if you still want to go that way...