The Rev 2 is a full port, and the Rev 3 is cut open and has a more aggressive port!
Bob could explain it a little further, I'll get him to post up on here.
Here is a some good info on our manifolds:
http://www.maperformance.com/search....nce+intake+evo
IF you click each picture it will give you information about each one!
Thank you,
Adam